[DOC] Replace "Edit on GitHub" workflow with contribution page

Most of the ViewHelper documentation is generated from the ViewHelper
source code. Therefore, the "Edit on GitHub" workflow is
counterproductive because it applies PRs to the reST files that will
be overwritten during the next generation run. Remove the
"Edit on GitHub" workflow and instead add a contribution page that
explains all the manual steps.

Conflicts:
	Documentation/Index.rst

Documentation/Contribution/Index.rst

@@ -0,0 +1,26 @@
+.. include:: /Includes.rst.txt
+
+============
+Contribution
+============
+
+Unlike most TYPO3 documentation, this manual does not support the
+popular *Edit on GitHub* workflow for manual contributions, as these
+documentation files are automatically generated from the ViewHelper
+source files - and overwritten on each generation run.
+
+Therefore, contribute to this documentation by editing the appropriate source
+files at
+
+*  https://github.com/FluidTYPO3/vhs/tree/development/Classes/ViewHelpers
+
+For example, adding a new core feature list item to the *asset* page at
+
+*  https://docs.typo3.org/other/fluidtypo3/vhs/main/en-us/fluidtypo3/vhs/latest/Asset.html
+
+is done by editing the class comment in
+
+*  https://github.com/FluidTYPO3/vhs/blob/development/Classes/ViewHelpers/AssetViewHelper.php
+
+To enrich the comment text you can use the common directives of the Markdown
+markup language.

Documentation/Index.rst

@@ -53,5 +53,7 @@ and iterators and array calculators and processors.
 .. toctree::
    :hidden:
 
+   Contribution/Index
+   Changelog
    Sitemap
    genindex

Documentation/Settings.cfg

@@ -11,8 +11,9 @@ copyright   = since 2012 by Claus Due & Contributors
 [html_theme_options]
 
 # "Edit on GitHub" button
-github_repository    = FluidTYPO3/vhs
-github_branch        = master
+# Do not show "Edit on GitHub" in automatically generated ViewHelper reference
+# github_repository    = FluidTYPO3/vhs
+# github_branch        = master
 
 # Footer links
 project_home         = https://extensions.typo3.org/extension/vhs
@@ -26,7 +27,7 @@ use_opensearch       =
 [intersphinx_mapping]
 
 # Official TYPO3 manuals
-# h2document     = https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/
+h2document     = https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/
 # t3cheatsheets  = https://docs.typo3.org/m/typo3/docs-cheatsheets/main/en-us/
 # t3contribute   = https://docs.typo3.org/m/typo3/guide-contributionworkflow/main/en-us/
 # t3coreapi      = https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/