Sandbox: PlexTraktSync & Omegabrr

[keldian]

new file:   docs/sandbox/apps/omegabrr.md
modified:   docs/sandbox/apps/plextraktsync.md
modified:   docs/sandbox/index.md
modified:   mkdocs.yml

Doc pages for PlexTraktSync and Omegabrr.

For new Sandbox app/role documentation, please confirm you have completed the following tasks:

• [x] App documentation page created
• [x] Reference added in docs/sandbox/index.md
• [x] Reference added in mkdocs.yml