F2 shows incorrect help topic for comparisons

[adamk]

Steps to Reproduce

1. Create a new document
2. Enter "$foo > $bar".
3. Highlight the ">" character.
4. Press the F2 key

The topic displayed for a ">" help search is the "$>" magic variable.

The actual help topic should be "X > Y".

Improve either F2 itself, or the help search functionality, to automatically know that a search for an operator such as ">" means the help topic "X > Y".