Doc: Update c3pm.yml description

[chloebourbion]

Note: for support questions, please use stackoverflow. This repository's issues are reserved for feature requests and bug reports.

• I'm submitting a ...

  • bug report
  • feature request
  • support request => Please do not submit support request here, see note at the top of this template.

• What is the current behavior?

Add missing c3pm.yml options, check explanation on the one already written

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

• What is the expected behavior?

• What is the motivation / use case for changing the behavior?

• Please tell us about your environment:

  • Version: XX
  • Browser: [all | Chrome XX | Firefox XX | Safari XX
    Mobile: Android X.X | iOS XX

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, gitter, etc)