chore(gitignore): update .gitignore to exclude build and site directories

Additions to the .gitignore file include the `build/` and `site/`
directories. This change prevents build artifacts and generated site
content from being tracked by git, reducing clutter in the repository
and ensuring that only source files are versioned.

Author: kzndotsh

.gitignore

@@ -161,8 +161,10 @@ config/settings*
 # MacOS
 .DS_Store
 
+build/
 docs-build/
 docs/site/
+site/
 
 # extensions
 tux/extensions/*