Documentation/maintainer-tip: Fix typos

Fix typos in documentation: a -> an.

Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241027125712.19141-1-algonell@gmail.com

Author: algonell

Documentation/process/maintainer-tip.rst

@@ -7,7 +7,7 @@ What is the tip tree?
 ---------------------
 
 The tip tree is a collection of several subsystems and areas of
-development. The tip tree is both a direct development tree and a
+development. The tip tree is both a direct development tree and an
 aggregation tree for several sub-maintainer trees. The tip tree gitweb URL
 is: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
 
@@ -121,7 +121,7 @@ The tip tree preferred format for patch subject prefixes is
 prefix. 'git log path/to/file' should give you a reasonable hint in most
 cases.
 
-The condensed patch description in the subject line should start with a
+The condensed patch description in the subject line should start with an
 uppercase letter and should be written in imperative tone.