Sync keyboard shortcut

[AdriandMartin]

Hi!

I've been looking for a keyboard shortcut for the sync action in the settings menu, but I've not found it

I'd like to have something like the F5 shortcut in a web browser (or any other, but the fact is that now it's only implemented as a button)

Thank you very much for this great app :)

[johannesjo]

Thanks for the suggestion! Makes sense to have this. PRs are welcome! :)