Add Getting Started instructions to the README (#33)

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

README.markdown

@@ -29,6 +29,18 @@ designing great APIs.*
 > All schemas target JSON Schema 2020-12, the dialect used by OpenAPI v3.1 and
 > later. Earlier JSON Schema dialects will be supported in the future.
 
+## :bookmark_tabs: Table of Contents
+
+- [:blue_book: Standards](#blue_book-standards)
+- [:rocket: Getting Started](#rocket-getting-started)
+      - [From Sourcemeta Schemas](#from-sourcemeta-schemas)
+      - [From GitHub Releases](#from-github-releases)
+      - [Using Git Submodules](#using-git-submodules)
+      - [Using Vendorpull](#using-vendorpull)
+- [:page_facing_up: License](#page_facing_up-license)
+- [:handshake: Contributing](#handshake-contributing)
+- [:email: Contact](#email-contact)
+
 ## :blue_book: Standards
 
 This library provides schemas that encode aspects of the following standards.
@@ -60,6 +72,103 @@ expressed as JSON Schema definitions.
 To request coverage of another standard, please [open an issue on
 GitHub](https://github.com/sourcemeta/std/issues).
 
+## :rocket: Getting Started
+
+While you can always copy-paste schemas directly, here are more convenient and
+maintainable ways to consume them.
+
+### From Sourcemeta Schemas
+
+We periodically publish the JSON Schema standard library to [Sourcemeta
+Schemas](https://schemas.sourcemeta.com/sourcemeta/std), our free service for
+hosting open-source schemas. Each schema gets a unique HTTPS URL that you can
+directly reference from your OpenAPI specifications using the
+[`$ref`](https://www.learnjsonschema.com/2020-12/core/ref) keyword. For
+example:
+
+```yaml
+schema:
+  type: object
+  properties:
+    email:
+      $ref: 'https://schemas.sourcemeta.com/sourcemeta/std/v0.0.1/ietf/email/address'
+```
+
+To de-reference and embed these external URLs when distributing your OpenAPI
+specification, use standard tools like [`redocly
+bundle`](https://redocly.com/docs/cli/commands/bundle).
+
+### From GitHub Releases
+
+We publish archives of the JSON Schema standard library to [GitHub
+Releases](https://github.com/sourcemeta/std/releases). Download and extract an
+archive to your preferred location, then reference the JSON files from your
+OpenAPI specifications using the
+[`$ref`](https://www.learnjsonschema.com/2020-12/core/ref) keyword with a
+relative path. For example:
+
+```yaml
+schema:
+  type: object
+  properties:
+    email:
+      $ref: "../path/to/sourcemeta-std/ietf/email/address.json"
+```
+
+### Using Git Submodules
+
+If your OpenAPI specification lives in a Git repository, you can add this
+library as a [git
+submodule](https://git-scm.com/docs/git-submodule). This approach keeps the
+schemas versioned alongside your code and ensures consistent access across your
+team. Add the submodule to your repository:
+
+```sh
+git submodule add https://github.com/sourcemeta/std std
+```
+
+Then reference the schemas using the
+[`$ref`](https://www.learnjsonschema.com/2020-12/core/ref) keyword with a
+relative path. For example:
+
+```yaml
+schema:
+  type: object
+  properties:
+    email:
+      $ref: './std/schemas/ietf/email/address.json'
+```
+
+### Using Vendorpull
+
+[Vendorpull](https://github.com/sourcemeta/vendorpull) is our tool for
+vendoring Git repositories, which we use across our projects. It provides an
+easier alternative to submodules by committing upstream contents directly into
+your repository while letting you easily manage and update them. Add this line
+to your `DEPENDENCIES` file:
+
+```
+std https://github.com/sourcemeta/std v<x.y.z>
+```
+
+Then pull the library into your `vendor` directory:
+
+```sh
+./vendor/vendorpull/pull std
+```
+
+Reference the schemas using the
+[`$ref`](https://www.learnjsonschema.com/2020-12/core/ref) keyword with a
+relative path. For example:
+
+```yaml
+schema:
+  type: object
+  properties:
+    email:
+      $ref: './vendor/std/schemas/ietf/email/address.json'
+```
+
 ## :page_facing_up: License
 
 While the project is publicly available on GitHub, it operates under a