pre-commit-config.yaml: exclude README.md from markdown-lint (#2971)

* pre-commit-config.yaml: exclude README.md from markdown-lint

markdown-lint: exclude README.md from 033-no-inline-html.md, i.e. allow inline HTML in README.md.

Addresses
#2947 (comment)

Co-authored-by: Nicklas Larsson <n_larsson@yahoo.com>

README.md

@@ -108,10 +108,6 @@ this issue, clean all the compiled files from the source code:
 make distclean
 ```
 
-
 ## Thanks to all contributors ❤
 
- <a href = "https://github.com/OSGeo/grass/graphs/contributors">
-   <img src = "https://contrib.rocks/image?repo=OSGeo/grass"/>
- </a>
-
+[![GRASS contributors](https://contrib.rocks/image?repo=OSGeo/grass "GRASS contributors")](https://github.com/OSGeo/grass/graphs/contributors)