Merge pull request #862 from kenjis/docs-HowToBuildDocs

docs: add "How to Build Shield Documentation"

admin/how_to_build_docs.md

@@ -0,0 +1,38 @@
+# How to Build Shield Documentation
+
+We use Material for MkDocs for our documentation.
+See https://squidfunk.github.io/mkdocs-material/getting-started/.
+
+## Requirements
+
+- Python3
+- pip
+
+## Installation
+
+```console
+pip3 install mkdocs
+pip3 install mkdocs-material
+pip3 install mkdocs-git-revision-date-localized-plugin
+```
+
+## Build the Docs
+
+```consolse
+mkdocs build
+```
+
+## See the Docs
+
+```consolse
+mkdocs serve
+```
+
+## Deploy Manually
+
+The documentation is built and deployed automatically by GitHub Actions. But if
+you need to deploy manually, run the following command:
+
+```console
+mkdocs gh-deploy
+```