Add AddToAny HELP

Created Community Documentation issue #2719127: Community Documentation for AddToAny

This will be referenced in the About section of HELP

Following is my review checklist w/ comments of what is included with this patch.

1. Short description of what the module does. It is displayed on the Extend or Modules page (in Drupal 8 or 7). It is the only texts users will see if the module is not enabled yet.

^-- This was actually already in place. One of the things this patch does at this location is to add the "?Help" icon as part of the help_hook call. However, the actual existing Description that is used in really not in conformance with the standard (IMO). Once the patch is in place, this might become more of an issue, and if so we will pick it up as a separate issue.

2. Description on links are displayed with the links on the Configuration and Structure pages and invite users to do something.

^-- This refers to the hover text ( or tooltip) in play when hovering over the link to /admin/config/system/addtoany . This looks OK to me.

3. Explanations on the administration pages. Ideally this should not be needed, but if they do they are short and do not duplicate the help page.

^-- Not need in this case.

4. Help page displayed by the Help module with three sections: What does the module do, what can users do with it, and a link to the online documentation here on drupal.org. This hook_help() text is in the my_module.module file.

^-- The bulk of the work for this patch resides here. It includes the three required section with descriptive text to help user understand the particulars of this module. Much of this information is derived from various artifacts on the web including Wikipedia, addtoany.com and /project/addtoany . It includes a link to community documentation that is picked up in this issue #2719127: Community Documentation for AddToAny. Also, Drupal standards call for a readme.txt file to be included with contributed projects. Since there is none at the moment, this issue will deal with that ... #2719131: Create AddToAny README.txt

Wordsmithing (copy/edit) of the text provided with this patch to any great deal is probably best reserved for after the readme.txt file is put into place. Since that is a .txt file it is easily edited by commenters, and then any major HELP text revision can be gleaned from THAT under a separate issue.

Removing me from the Assigned * tag to encourage a broader community review.