bug#34080: 27.0.50, 26.1; undocumented key bindings for *vc-diff*

[Van L]

Hello,

The *Help* buffer for diff-mode.el is better 
if the following key bindings are documented 

#+NAME: undocumented-key-bindings
| key   | binding        |
|-------+----------------|
| TAB   | diff-hunk-next |
| S-TAB | diff-hunk-prev |

the above make more sense than the following

#+NAME: existing-key-bindings-documented
| key   | binding        |
|-------+----------------|
| C-M-i | diff-hunk-next |
| M-n   |                |
|-------+----------------|
| M-p   | diff-hunk-prev |

And, for the word "hunk" to link to a Glossary's 
entry like for example

http://www-history.mcs.st-and.ac.uk/Glossary/oblong_number.html

is a feature to have unless it is already therein.