docs: actually add main.py module to git

Signed-off-by: Andy Goldstein <andy.goldstein@redhat.com>

docs/main.py

@@ -0,0 +1,67 @@
+# Copyright 2023 The KCP Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from mkdocs_macros import fix_url
+import copy
+
+
+def define_env(env):
+    """
+    This is the hook for defining variables, macros, and filters. See
+    https://mkdocs-macros-plugin.readthedocs.io/en/latest/macros/#the-define_env-function for more details.
+
+    :param env: the Jinja2 environment
+    """
+
+    @env.macro
+    def section_items(page, nav, config):
+        """
+        Returns a list of all pages that are siblings to page.
+
+        :param page: the current page. This will typically be an index.md page.
+        :param nav: the mkdocs navigation object.
+        :param config: the mkdocs config object.
+        :return: a list of all the sibling pages.
+        """
+
+        if page.parent:
+            children = page.parent.children
+        else:
+            children = nav.items
+
+        siblings = []
+        for child in children:
+            if child is page:
+                # don't include the passed in page in the list
+                continue
+            if child.is_section:
+                # don't include sections
+                continue
+            if child.file.name == 'index':
+                # don't include index pages
+                continue
+
+            # Because some pages might not have been loaded yet, we have to do so now, to get title/metadata.
+            child.read_source(config)
+
+            # Copy so we don't modify the original
+            child = copy.deepcopy(child)
+
+            # Have to fix the URL - see
+            # https://mkdocs-macros-plugin.readthedocs.io/en/latest/tips/#how-do-i-deal-with-relative-links-to-documentsimages
+            child.file.url = fix_url(child.url)
+
+            siblings.append(child)
+
+        return siblings