Update documentation for hosting (#6)

* update instructions to build documentation locally only
* install PyEarthTools packages too for document generation
* use conda to install dependencies to generate the documentation
* fix doc generation + reindent mkdocs.yml to be consistent
- fix generation script
- fix options of mkdocstrings
- update path of packages to list

* move EDIT 101 content, add warnings about documentation state

* remove large (37 MB) gif from docs assets
* add disclaimer about documentation audience
* move old documentation out of packages as it is not a Python package
* add warning about state of the docs
* update path to Python packages for document generation
* fix (again) path to packages for doc generation
* back to instructions using a virtual environment for doc generation

This makes it simpler to have the same installation process for manual
installation and CI.

* add CI to build the documentation
* remove unused setting
* fix path for doc generator script

* Update docs.yml

change branch used to generated the documentation in CI/CD.

* removed github pages automation

Author: jennan