README: adapt main repository and contribution

Point to the GitHub repository as the main repository and adapt the
contribution style to GitHub PRs.

Signed-off-by: Marco Felsch <[email protected]>

Author: Marco Felsch

README.rst

@@ -23,13 +23,6 @@ Seamless transitions are possible (e.g. to *Weston* having the same image
 configured as background). Depending on the SoC used, the same format might be
 required to achieve that.
 
-For questions, feedback, patches, please send a mail to::
-
-  [email protected]
-
-Note: you must be subscribed to post to this mailing list. You can do so by
-sending an empty mail to ``[email protected]``.
-
 Splash Image Generation
 -----------------------
 
@@ -121,14 +114,9 @@ Contributing
 
 The Git repository for this software can be found at::
 
-  https://git.pengutronix.de/cgit/platsch
-
-Any patches should be sent to the mailing list above. Please prefix your
-subject with "[PATCH platsch]" (when sending patches with Git, see the
-git-config manpage for the option ``format.subjectPrefix``).
-Mails sent to this mailing list are also archived at::
+  https://github.com/pengutronix/platsch
 
-  https://lore.pengutronix.de/oss-tools
+Contribution can be done via GitHub Pull-Requests.
 
 This project uses the Developer's Certificate of Origin, as stated in the file
 DCO bundled with this software, using the same process as for the Linux kernel::