Improve lronac2isis error message and update app docs

[tgiroux]

Description

Adds to the if(id.mid(13, 3) != "EDR") exception message to include information about using pds2isis for RDR/CDR. Adds some clarity to the app documentation so that users know lronac2isis is for EDR, and are referred to pds2isis for RDR/CDR.

Related Issue

#4055

Motivation and Context

Documentation improvement.

How Has This Been Tested?

Existing checks for non-EDR formats are working as intended. Tested with EDR, CDR, and RDR files found here. The app correctly ingests for EDR and throws exceptions for CDR/RDR. I don't see how a CDR image could slip through the cracks without causing an exception.

Existing tests for lronac2isis still pass with this PR.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Documentation change (update to the documentation; no code change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have read and agree to abide by the Code of Conduct
• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have added myself to the .zenodo.json document.
• I have added any user impacting changes to the CHANGELOG.md document.

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.