pgsql: doc: Remove mention of Git protocol support

doc: Remove mention of Git protocol support

The project Git server hasn't supported cloning with the Git protocol
in a very long time, but the documentation never got the memo. Remove
the mention of using the Git protocol, and while there wrap a mention
of Git in <productname> tags.

Backpatch down to all supported versions.

Author: Daniel Gustafsson <daniel(at)yesql(dot)se>
Reported-by: Gurjeet Singh <gurjeet(at)singh(dot)im>
Reviewed-by: Nathan Bossart <nathandbossart(at)gmail(dot)com>
Reviewed-by: Jacob Champion <jacob(dot)champion(at)enterprisedb(dot)com>
Reviewed-by: Gurjeet Singh <gurjeet(at)singh(dot)im>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/CABwTF4WMiMb-KT2NRcib5W0C8TQF6URMb+HK9a_=rnZnY8Q42w@mail.gmail.com
Backpatch-through: 13

Branch
------
REL_14_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/d4542415c38ead3c356abbfd476be63b9101ffc0

Modified Files
--------------
doc/src/sgml/sourcerepo.sgml | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)