Feature Request: add config options to change picker mappings

[benelan]

Issue Description

Type: feature request

Describe what happened (or what feature you want)

I'd like the ability to change the Telescope mappings set by this plugin. Specifically, I use <C-b> to scroll the preview up, and I always accidentally open issues/prs in the browser when using Octo.

Describe what you expected to happen

The ability to change Telescope mappings, which are currently hard-coded.

How to reproduce it (as minimally and precisely as possible)

N/A (not a bug)

Tell us your environment

N/A (not a bug)

Anything else we need to know?

I submitted a pull request for this issue: #448