doc: Firefox from version 60 moved audio to the main process

README.md

@@ -179,6 +179,7 @@ default. Fortunately, it's possible to add those path by hand. Add "/dev/snd/"
 to "security.sandbox.content.write_path_whitelist" parameter in
 `about:config`. Note that trailing slash in "/dev/snd/" is required.
 
+
 Firefox 58 tabs crashing when trying to play audio
 --------------------------------------------------
 
@@ -189,6 +190,10 @@ with subsequent process termination. Exception can be added by setting parameter
 accepts a comma separated list of system call numbers. Add there `16` for
 x86-64, or `54` for x86 or ARM.
 
+Firefox 60 tighened its content sandbox more, but at the same time moved audio
+accesses from content processes to the main process. From Firefox 60 onwards no
+changes to the sandbox settings are necessary.
+
 License
 =======