docs: add back-navigation and standardize Used By (#241)

* docs: add back-navigation link and standardize Used By section

- Add '← Back to cpp-linter hub' link near top of README (#10)
- Add link to hub site from 'Used By' section (#9)

* docs: use shields.io badge for back-navigation link

* Fix badge duplication in README.md

Author: shenxianpeng

README.md

@@ -5,6 +5,7 @@
 [![codecov](https://codecov.io/gh/cpp-linter/cpp-linter-hooks/branch/main/graph/badge.svg?token=L74Z3HZ4Y5)](https://codecov.io/gh/cpp-linter/cpp-linter-hooks)
 [![Test](https://github.com/cpp-linter/cpp-linter-hooks/actions/workflows/test.yml/badge.svg)](https://github.com/cpp-linter/cpp-linter-hooks/actions/workflows/test.yml)
 [![CodeQL](https://github.com/cpp-linter/cpp-linter-hooks/actions/workflows/codeql.yml/badge.svg)](https://github.com/cpp-linter/cpp-linter-hooks/actions/workflows/codeql.yml)
+[![cpp-linter hub](https://img.shields.io/badge/%F0%9F%8F%A0_cpp--linter_hub-%E2%86%90_home-22863a)](https://cpp-linter.github.io/)
 
 A pre-commit hook repository for C/C++ projects that installs and runs
 `clang-format` and `clang-tidy` through the
@@ -329,6 +330,8 @@ Two self-contained templates plus quick snippets for other common setups.
 ![IMSY-DKFZ](https://github.com/IMSY-DKFZ.png?size=20) IMSY-DKFZ and
 [many more](https://github.com/search?q=repo%3A%20https%3A%2F%2Fgithub.com%2Fcpp-linter%2Fcpp-linter-hooks&type=code).
 
+See the [cpp-linter hub](https://cpp-linter.github.io/) for the full list of organizations using cpp-linter tools.
+
 ## FAQ
 
 ### What's the difference between [`cpp-linter-hooks`](https://github.com/cpp-linter/cpp-linter-hooks) and [`mirrors-clang-format`](https://github.com/pre-commit/mirrors-clang-format)?