Notes number in graph is not obvious.

Years ago there was a feature for showing number of notes for a commit in the graph.

But over the years it has format [<number>]. It appears on the graph where name of the branch is usually shown and confuses (https://github.com/gitlabhq/gitlabhq/issues/6931, https://github.com/gitlabhq/gitlabhq/issues/3684) those who don't know the meaning of these numbers, since it looks like a branch name or something.

I propose to rephrase it from [<number>] to [<number> note(s)] to be more user-friendly.