PR: Some last minute fixes before releasing Spyder 6

[ccordoba12]

Description of Changes

• Show in-app appeal dialog the fifth time Spyder starts. We discussed about that with the UX team and think it's a good idea. After that, we'll only show the status bar widget.
• Hide config file connection method in ConnectionDialog of the Remote client. That's necessary because it's not implemented yet.
• Improve a couple of module docstrings in our API.

Issue(s) Resolved

Fixes #

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: @ccordoba12