docs: port foo.rst to foo.md

I like to write documentation in MarkDown better than in `*.rst`.

First step is to have new package documentation in MarkDown. So port the
reference `foo.rst` to `foo.md.

Author: NeroBurner

docs/conf.py

@@ -84,7 +84,7 @@
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build', '_venv', 'rtfd-css', 'packages/pkg/foo.rst', 'old-wiki']
+exclude_patterns = ['_build', '_venv', 'rtfd-css', 'packages/pkg/foo.md', 'old-wiki']
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.

docs/packages/pkg/foo.md

@@ -0,0 +1,22 @@
+```{spelling}
+
+foo
+```
+
+```{index} single: unsorted ; foo
+```
+
+(pkg.foo)=
+
+# foo
+
+-  [Official](https://official_foo)
+-  [Hunterized](https://github.com/cpp-pm/foo)
+-  [Example](https://github.com/cpp-pm/hunter/blob/master/examples/foo/CMakeLists.txt)
+-  Added by [foo_developer](https://github.com/foo_developer) ([pr-N](https://github.com/cpp-pm/hunter/pull/N))
+
+```{literalinclude} /../examples/foo/CMakeLists.txt
+:language: cmake
+:start-after: "# DOCUMENTATION_START {"
+:end-before: "# DOCUMENTATION_END }"
+```