Unify community forum references and move to include file

[benjaoming]

We repeat variations of this a lot of times:

For further assistance, please report the issue on our `Community Forums <https://community.learningequality.org/>`_, stating the operating system and Kolibri version.

Especially in the troubleshooting section. Perhaps we can figure out a way to have it included as a nice little box that can be included here and there instead of repeating variations of the same texts.

[kaushalkrgupta02]

Hi,
button with text 'Community Forums' with a side tooltip have that text apperswhen mouse hover can help