[5.4] Readme howto contribute (#45568)

Added 'How to submit code to the Joomla CMS using a PR' link to README.[md|txt]

---------

Signed-off-by: BrianTeeman <[email protected]>

Author: brianteeman

README.md

@@ -67,6 +67,7 @@ Do you want to improve Joomla?
 --------------------
 * Where to [request a feature](https://issues.joomla.org)?
 * How do you [report a bug](https://docs.joomla.org/Special:MyLanguage/Filing_bugs_and_issues) on the [Issue Tracker](https://issues.joomla.org)?
+* How to [submit code](https://manual.joomla.org/docs/get-started/git/) to the Joomla CMS using a Pull Request?
 * Get Involved: Joomla! is community developed software. [Join the community](https://volunteers.joomla.org).
 * Documentation for [Developers](https://manual.joomla.org/).
 * Documentation for [Web designers](https://docs.joomla.org/Special:MyLanguage/Web_designers).

README.txt

@@ -65,6 +65,7 @@ Joomla! CMS™
 12- Do you want to improve Joomla?
 	* Where to request a feature? https://issues.joomla.org
 	* How do you report a bug? https://docs.joomla.org/Special:MyLanguage/Filing_bugs_and_issues
+	* How to submit code to the Joomla CMS using a Pull Request? https://manual.joomla.org/docs/get-started/git/
 	* Get Involved: Joomla! is a community developed software. Join the community at https://volunteers.joomla.org
 	* Documentation for Developers: https://manual.joomla.org/
 	* Documentation for Web designers: https://docs.joomla.org/Special:MyLanguage/Web_designers