Docs: credit ported work and cover today's merged changes

Add CREDITS.md, listing the projects the fork is built on and every
change ported from upstream WiiCompiled and other forks, with author and
source commit, taken from the commit messages. Link it from the README,
THIRD-PARTY-NOTICES.md and a new porting note in CONTRIBUTING.md.

Document adaptive_resolution in OPENXR.md, the 4 KiB page constant and
NEON mixing in the README, the Mozilla CA bundle in the notices, and draft
the frame-beta-3 release notes for what PRs #5 to #10 merged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Axv1Y43Lu5a5rSSLUyU5BB

CONTRIBUTING.md

@@ -39,9 +39,19 @@ That's ok, but rules apply:
   game (hardware comparison, logs, whatever fits).
 - Review feedback. It's about the code, not about you ;).
 
+## Porting from other projects
+
+This fork takes fixes from upstream WiiCompiled and other forks. When you port one:
+
+- name the source repository and commit in the commit message ("Ported from owner/repo abc1234");
+- keep the original author on the commit when the change is taken as is, and say what you changed
+  when it is adapted;
+- add a line to [`CREDITS.md`](CREDITS.md), and check the source's license is compatible with
+  GPL v3.0.
+
 ## Bug reports
 
-See the FAQ in the [README](README.md)
+See [Reporting problems](README.md#reporting-problems) in the README.
 
 ## A note on related projects