docs: add an OAuth2.0 credential helper for AOL accounts

Yahoo and AOL, both advertise that they support app passwords for third-party
applications. But generating app passwords for them is broken and unreliable
for quite some time now. Yahoo already had an OAuth2.0 credential helper
added in the documentation, so I thought it would be a good idea to add one
for AOL accounts as well, which is more reliable and secure.

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: AdityaGarg8

Documentation/git-send-email.adoc

@@ -600,6 +600,9 @@ available online. Community maintained credential helpers are also available:
 	- https://github.com/AdityaGarg8/git-credential-email[git-credential-yahoo]
 	  (cross platform, dedicated helper for authenticating Yahoo accounts)
 
+	- https://github.com/AdityaGarg8/git-credential-email[git-credential-aol]
+	  (cross platform, dedicated helper for authenticating AOL accounts)
+
 You can also see linkgit:gitcredentials[7] for more OAuth based authentication
 helpers.