Updating documentation for various elements

[antonhibl]

Addressing #453. This PR primarily adds documentation updates to affect the sphynx docs; currently further updates and documents code methods and parameters in the following areas(this list will be updated with checks as I go through the various parts of the codebase):

Library

• USGSCSM Distortion Class
• USGSCSM Utilities Class
• USGSCSM Astro Plugin Class
• USGSCSM Astro Frame Sensor Model Class
• USGSCSM Linescan Sensor Model Class
• USGSCSM SAR Sensor Model Class

Cameras

• All camera examples updated and rendering

Creating an Environment

• Install instructions shifted to the top and updated to fix all rendering.
• If installation with pip is supported add that.

Fixing Typos or Incorrect Links

Addressing and fixing various incorrect links and typos as I go through the code. So far I have found:

• Fixed broken links in source/docs/index.rst (USGS-Astrogoelogy -> DOI-USGS)

Licensing

This project is mostly composed of free and unencumbered software released into the public domain, and we are unlikely to accept contributions that are not also released into the public domain. Somewhere near the top of each file should have these words:

This work is free and unencumbered software released into the public domain. In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain.

• I dedicate any and all copyright interest in this software to the public domain. I make this dedication for the benefit of the public at large and to the detriment of my heirs and successors. I intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

[Kelvinrr]

Great job with the docs, just some things inline.