Suggestion: Update documentation for transcode folders

Hi,

In the current docs at https://github.com/plexinc/pms-docker (and on docker hub), the recommendation for mapping of volumes is:

-v <path/to/plex/database>:/config \
-v <path/to/transcode/temp>:/transcode \
-v <path/to/media>:/data \

Mapping transcoding makes total sense as it takes up lots of space and the user might want to offload that to a data drive vs where the container resides.

That being said, I think this should be revised to:

-v <path/to/plex/database>:/config \
-v <path/to/transcode/temp>:/transcode \
-v <path/to/transcode/cache>/Sync+:/config/Library/Application Support/Plex Media Server/Cache/Transcode/Sync+ \
-v <path/to/transcode/cache>/Sync:/config/Library/Application Support/Plex Media Server/Cache/Transcode/Sync \
-v <path/to/media>:/data \

This is where the transcoding occurs for synchronized media, and it also eats up a ton of space when a conversion is in progress. I understand this would be external as part of the config folder, but that config folder is likely where the container resides, and potentially not a large data drive.

Root cause
I actually think this should be configured completely different where the Sync(+) folders are part of the transcode folder period on all systems, not the config/cache folder, docker or not. But at least this works here.