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

.github/ISSUE_TEMPLATE/documentation.yaml

@@ -0,0 +1,15 @@
+name: "Documentation"
+description: "Create an issue to improve the documentation"
+labels: ["documentation"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Create a new issue regarding the InvenTree documentation
+  - type: textarea
+    id: repro
+    attributes:
+      label: Body of the issue
+      description: Please provide one distinct thing to fix or a clearly defined enhancment
+    validations:
+      required: true

.github/workflows/check_docs_config.yaml

@@ -0,0 +1,27 @@
+name: Documentation Config Checks
+
+on:
+  push:
+    branches-ignore:
+      - l10*
+
+  pull_request:
+    branches-ignore:
+      - l10*
+
+jobs:
+
+  mkdocs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v2
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.9
+      - name: Run Checks
+        run: |
+          pip install pyyaml
+          python docs/ci/check_mkdocs_config.py