docs: backporting: fix a typo

Fix a typo in documentation.

Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241002212150.11159-1-algonell@gmail.com

Author: algonell

Documentation/process/backporting.rst

@@ -74,7 +74,7 @@ your source tree. Don't forget to cherry-pick with ``-x`` if you want a
 written record of where the patch came from!
 
 Note that if you are submitting a patch for stable, the format is
-slightly different; the first line after the subject line needs tobe
+slightly different; the first line after the subject line needs to be
 either::
 
     commit <upstream commit> upstream