Documentation integration (#4653)

* Add documentation under docs/ directory

* Add CI workflow for mkdocs configuration checking

* Add documentation issue template

* update pip-tools?

* Update .gitignore files

* Fix .gitignore rules

* Improve release notes page

* remove references to old repo

docs/main.py

@@ -0,0 +1,29 @@
+"""Main entry point for the documentation build process"""
+
+import os
+
+
+def define_env(env):
+    """Define custom environment variables for the documentation build process"""
+
+    @env.macro
+    def listimages(subdir):
+        """Return a listing of all asset files in the provided subdir"""
+
+        here = os.path.dirname(__file__)
+
+        directory = os.path.join(here, 'docs', 'assets', 'images', subdir)
+
+        assets = []
+
+        allowed = [
+            '.png',
+            '.jpg',
+        ]
+
+        for asset in os.listdir(directory):
+
+            if any([asset.endswith(x) for x in allowed]):
+                assets.append(os.path.join(subdir, asset))
+
+        return assets