Issue #3423402: cspell doc page

Closes #3423402

docs/help/documentation.md

@@ -14,6 +14,8 @@ docker run --rm -it -p 8000:8000 -v ${PWD}:/docs squidfunk/mkdocs-material
 
 That will serve a site locally.
 
+If you do not have `docker` in your system, you can get [MkDocs](https://www.mkdocs.org/getting-started/) and [MkDocs Material](https://squidfunk.github.io/mkdocs-material/getting-started/) installed, and then you can do `mkdocs serve .`.
+
 ## Check for spelling errors
 
 You can check the site for spelling errors before committing with this commands: