DOCS: document JPEG XL default effort change

Document the change in 7607432127.

DOCS/interface-changes.rst

@@ -53,6 +53,7 @@ Interface changes
     - change --screenshot-tag-colorspace default value from `no` to `yes`
     - undeprecate vf_sub
     - add `--tone-mapping=st2094-40` and `--tone-mapping=st2094-10`
+    - change `--screenshot-jxl-effort` default from `3` to `4`.
  --- mpv 0.35.0 ---
     - add the `--vo=gpu-next` video output driver, as well as the options
       `--allow-delayed-peak-detect`, `--builtin-scalers`,

DOCS/man/options.rst

@@ -4422,7 +4422,7 @@ Screenshot
 
 ``--screenshot-jxl-effort=<1-9>``
     Set the JPEG XL compression effort. Higher effort (usually) means better
-    compression, but takes more CPU time. The default is 3.
+    compression, but takes more CPU time. The default is 4.
 
 ``--screenshot-sw=<yes|no>``
     Whether to use software rendering for screenshots (default: no).