doc/gitremote-helpers: fix more missing single-quotes

There are a few cases left in gitremote-helpers.txt that are missing a
closing quote, so you end up with:

  'option deepen-since <timestamp>

with a stray opening quote instead of rendering correctly in italics.
These should have been part of 51d41dc (doc/gitremote-helpers: fix
missing single-quote, 2024-03-07), but apparently my eyesight is not
what it once was. Hopefully this is now all of them.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

Documentation/gitremote-helpers.txt

@@ -470,14 +470,14 @@ set by Git if the remote helper has the 'option' capability.
 'option depth' <depth>::
 	Deepens the history of a shallow repository.
 
-'option deepen-since <timestamp>::
+'option deepen-since' <timestamp>::
 	Deepens the history of a shallow repository based on time.
 
-'option deepen-not <ref>::
+'option deepen-not' <ref>::
 	Deepens the history of a shallow repository excluding ref.
 	Multiple options add up.
 
-'option deepen-relative {'true'|'false'}::
+'option deepen-relative' {'true'|'false'}::
 	Deepens the history of a shallow repository relative to
 	current boundary. Only valid when used with "option depth".