Remove $sitename from (rendered content in) help seeds

[cellio]

We seed certain help topics (how to ask, FAQ, not sure if there are others) with text that includes "$sitename". We don't auto-replace that with the actual name, which means we have to edit those topics when we launch new communities.

I propose that we make the help seeds usable in their initial states, so mods can enhance them but don't have to. Replacing "$sitename" with "this site" or just dropping it in some places can work. I just edited the how-to-ask page on some communities to remove two name references that could be generalized, as a workaround to a bug. We could still include HTML comments to indicate places mods might want to edit/enhance and we could use "$sitename" in those comments to give mods something to search for.

Can we make our help seeds work out of the box without making them too vague to be useful?