Improving issues with issue-comments

[Denubis]

We all have had "fun" removing the pro-forma text in our default issues. When commenting on a different project, I saw that they took advantage of HTML comments to provide instructional text (as well as different types of issue buttons for different types of instructional text.

The below is a test of our default comment instructions, which should not appear in cursory viewing of the issue (but should appear when viewing source)

Comment start:

Comment end:

An HTML comment takes the form of: <!-- Please delete ... -->, but browsers do not render it.

Comment start:

Comment end: The above test is a test of a multi-paragraph comment. You should not see the normal proforma "email team" in normal view, but it should be visible when viewing source. Added comment start/end delimiters just so we can see that we're not seeing what's inside them. Credit to the sevtech-ages repo for showing this technique to me.