Added documentation on using variables in snippets (#2006)
Added documentation on using variables in snippets (#2006)

* variables do not work in snippets included using Snippets extension
* workaround: use macros plugin to define snippets (as described here https://mkdocs-macros-plugin.readthedocs.io/en/latest/advanced/#including-snippets-in-pages)
squidfunk/mkdocs-material,squidfunk/mkdocs-material,squidfunk/mkdocs-material,squidfunk/mkdocs-material