Update docs considering changes on Rocky 24R2

[igortg]

• Explicit list PyRocky differences on GetTimeSet and GetCurves methods
• Use "PrePost Scripting" instead of "PrePost API" to refers to the Rocky scripting feature (changed on 24R2)
• Fix the docstring content of launcher.py
• CONTRIBUTING.md now points to the PyRock Contributing section of PyRocky Developer's Guide
• Adds a small intro to the Developer's guide index page and remove the "How to Contribute" card (not something we want to highlight for the casual user)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.26%. Comparing base (3b5b30d) to head (efc4a2a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #63 +/- ## ======================================= Coverage 94.26% 94.26% ======================================= Files 5 5 Lines 157 157 ======================================= Hits 148 148 Misses 9 9 ```

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