SubmitAPatch wiki page has broken link to coding style

[Rebecca Cran]

In commit cbcf09872a936ccefef6a34298046d3b9aefc148 on February 25th 
CODING_STYLE.rst was moved into the developer manual. So, the "Use the 
QEMU coding style" section of 
https://wiki.qemu.org/Contribute/SubmitAPatch should probably be updated 
to link to:

https://gitlab.com/qemu-project/qemu/-/blob/master/docs/devel/style.rst
--
Rebecca Cran