Code review comment for ~chris.sanders/charm-grafana:fix-template

> I'm not seeing commit be44ba7's changes in this diff. I'm going to guess
> those are already merged into master and this MR is just confused.

Yes it's showing the last commit of master, I presume to give an idea where this was based. That commit is already on master not part of this change.

> Other than spelling mistake which won't affect functionality and some
> suggestions around the render_custom, I'm good with this rolling out, but
> would like to defer to IS reviewers for criticality of comments.

I've fixed they typo and added a bug to charm-helpers, thanks.