[Feature Request] Include theme Feedlish

[iophobia]

Is your feature request related to a problem? Please describe.
The bundled Feedly theme is already quite nice. I did however to transition to the Feedlish fork by gravemind some time ago in previous deployments because (IMHO) it's easier on the eye and has better spacing in list mode.

Describe the solution you'd like
Add Feedlish instead or in addition to Feedly theme in docker files.

Additional context
Alternatively, to not bloat the install, I'd like to know the internal path to the themes.local folder in your setup.