chore(git): use "main" branch instead of "master" branch

Documentation/For_ops/Realese/HOWTO_Create_a_release.md

...tation/For_ops/UPGRADE/UPGRADE_from_v2.10.0_to_v2.11.0.md

...tation/For_ops/UPGRADE/UPGRADE_from_v2.11.0_to_v2.12.0.md

...tation/For_ops/UPGRADE/UPGRADE_from_v2.12.0_to_v2.13.0.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.5.0_to_v2.6.0.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.6.0_to_v2.7.0.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.7.0_to_v2.8.0.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.8.0_to_v2.9.0.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.9.0_to_v2.9.1.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.9.1_to_v2.9.2.md

...entation/For_ops/UPGRADE/UPGRADE_from_v2.9.2_to_v2.9.3.md

...ntation/For_ops/UPGRADE/UPGRADE_from_v2.9.3_to_v2.10.0.md

grumphp.yml

src/Template/Element/Pages/footer.ctp