Fix non-exemplar template parity with cookiecutter output

Restructure template/README.md.jinja so the heading, badges,
description, license, and usage sections are shared between
exemplar and non-exemplar output, matching what cookiecutter
produced. Previously the non-exemplar branch rendered only "TODO"
with no heading or badges.

Guard exemplar-specific paths in .gitattributes.jinja (template/,
copier/) and .pre-commit-config.yaml.jinja exclude pattern so
generated non-exemplar projects don't reference directories they
don't contain.

Fix extra blank line in CONTRIBUTING.md.jinja rendering and remove
the include-path NOTE that main deliberately removed.

Author: steve-downey

README.md

@@ -153,6 +153,10 @@ What follows is an example of a Beman library README.
 
 # beman.exemplar: A Beman Library Exemplar
 
+<!--
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+-->
+
 <!-- markdownlint-disable line-length -->
 [![Library Status](https://raw.githubusercontent.com/bemanproject/beman/refs/heads/main/images/badges/beman_badge-beman_library_under_development.svg)](https://github.com/bemanproject/beman/blob/main/docs/beman_library_maturity_model.md#the-beman-library-maturity-model)
 [![Continuous Integration Tests](https://github.com/bemanproject/exemplar/actions/workflows/ci_tests.yml/badge.svg)](https://github.com/bemanproject/exemplar/actions/workflows/ci_tests.yml)
@@ -359,9 +363,3 @@ include an appropriate `beman.exemplar` header from your source code.
 ```c++
 #include <beman/exemplar/exemplar.hpp>
 ```
-
-> [!NOTE]
->
-> `beman.exemplar` headers are to be included with the `beman/exemplar/` prefix.
-> Altering include search paths to spell the include target another way (e.g.
-> `#include <exemplar.hpp>`) is unsupported.

template/.gitattributes.jinja

@@ -1,6 +1,8 @@
 infra/** linguist-vendored
+{% if generating_exemplar -%}
 template/** linguist-vendored
 copier/** linguist-vendored
+{% endif -%}
 *.bib -linguist-detectable
 *.tex -linguist-detectable
 papers/* linguist-documentation

template/.pre-commit-config.yaml.jinja

@@ -48,4 +48,8 @@ repos:
     - id: beman-tidy
 
 {% endif %}
+{% if generating_exemplar -%}
 exclude: 'template/|copier/|infra/|port/'
+{% else -%}
+exclude: 'infra/|port/'
+{% endif -%}

template/CONTRIBUTING.md.jinja

@@ -105,8 +105,9 @@ ctest --test-dir build
 
 The file `./lockfile.json` configures the list of dependencies and versions that will be
 acquired by FetchContent.
+{% if generating_exemplar %}
 
-{% if generating_exemplar %}## Developing The Copier Template
+## Developing The Copier Template
 
 This repository doubles as both the exemplar library and the Copier template used to stamp
 new Beman libraries.

template/README.md.jinja

@@ -152,31 +152,46 @@ The consistency check renders from a `.git`-free temporary snapshot of the repos
 
 What follows is an example of a Beman library README.
 
-# beman.exemplar: A Beman Library Exemplar
+{% endif %}
+# beman.{{project_name}}: {{description}}
+
+<!--
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+-->
 
 <!-- markdownlint-disable line-length -->
 [![Library Status](https://raw.githubusercontent.com/bemanproject/beman/refs/heads/main/images/badges/beman_badge-beman_library_under_development.svg)](https://github.com/bemanproject/beman/blob/main/docs/beman_library_maturity_model.md#the-beman-library-maturity-model)
-[![Continuous Integration Tests](https://github.com/bemanproject/exemplar/actions/workflows/ci_tests.yml/badge.svg)](https://github.com/bemanproject/exemplar/actions/workflows/ci_tests.yml)
-[![Lint Check (pre-commit)](https://github.com/bemanproject/exemplar/actions/workflows/pre-commit-check.yml/badge.svg)](https://github.com/bemanproject/exemplar/actions/workflows/pre-commit-check.yml)
-[![Coverage](https://coveralls.io/repos/github/bemanproject/exemplar/badge.svg?branch=main)](https://coveralls.io/github/bemanproject/exemplar?branch=main)
+[![Continuous Integration Tests](https://github.com/{{owner}}/{{project_name}}/actions/workflows/ci_tests.yml/badge.svg)](https://github.com/{{owner}}/{{project_name}}/actions/workflows/ci_tests.yml)
+[![Lint Check (pre-commit)](https://github.com/{{owner}}/{{project_name}}/actions/workflows/pre-commit-check.yml/badge.svg)](https://github.com/{{owner}}/{{project_name}}/actions/workflows/pre-commit-check.yml)
+[![Coverage](https://coveralls.io/repos/github/{{owner}}/{{project_name}}/badge.svg?branch=main)](https://coveralls.io/github/{{owner}}/{{project_name}}?branch=main)
 ![Standard Target](https://github.com/bemanproject/beman/blob/main/images/badges/cpp29.svg)
-[![Compiler Explorer Example](https://img.shields.io/badge/Try%20it%20on%20Compiler%20Explorer-grey?logo=compilerexplorer&logoColor=67c52a)](https://godbolt.org/z/4qEPK87va)
+{% if generating_exemplar %}[![Compiler Explorer Example](https://img.shields.io/badge/Try%20it%20on%20Compiler%20Explorer-grey?logo=compilerexplorer&logoColor=67c52a)](https://godbolt.org/z/4qEPK87va)
+{% endif %}
 <!-- markdownlint-restore -->
 
+{% if generating_exemplar %}
 `beman.exemplar` is a minimal C++ library conforming to [The Beman Standard](https://github.com/bemanproject/beman/blob/main/docs/beman_standard.md).
 This can be used as a template for those intending to write Beman libraries.
 It may also find use as a minimal and modern C++ project structure.
+{% else %}
+`beman.{{project_name}}` is (... TODO: description).
+{% endif %}
 
-**Implements**: `std::identity` proposed in [Standard Library Concepts (P0898R3)](https://wg21.link/P0898R3).
+{% if generating_exemplar %}
+**Implements**: `std::identity` proposed in [Standard Library Concepts ({{paper}})](https://wg21.link/{{paper}}).
+{% else %}
+**Implements**: `std::todo` proposed in [TODO ({{paper}})](https://wg21.link/{{paper}}).
+{% endif %}
 
 **Status**: [Under development and not yet ready for production use.](https://github.com/bemanproject/beman/blob/main/docs/beman_library_maturity_model.md#under-development-and-not-yet-ready-for-production-use)
 
 ## License
 
-`beman.exemplar` is licensed under the Apache License v2.0 with LLVM Exceptions.
+`beman.{{project_name}}` is licensed under the Apache License v2.0 with LLVM Exceptions.
 
 ## Usage
 
+{% if generating_exemplar %}
 `std::identity` is a function object type whose `operator()` returns its argument unchanged.
 `std::identity` serves as the default projection in constrained algorithms.
 Its direct usage is usually not needed.
@@ -364,9 +379,3 @@ include an appropriate `beman.{{project_name}}` header from your source code.
 ```c++
 #include <beman/{{project_name}}/{{project_name}}.hpp>
 ```
-
-> [!NOTE]
->
-> `beman.{{project_name}}` headers are to be included with the `beman/{{project_name}}/` prefix.
-> Altering include search paths to spell the include target another way (e.g.
-> `#include <{{project_name}}.hpp>`) is unsupported.