Release v0.3.69 RTC Product Guide updates

[hjkristenson]

Updates to documentation including:

• new URLs in Sentinel-1 document
• updates to pixel spacing sections
• removing caveats that the option is not yet in Vertex
• adding illustration to compare 10, 20 and 30-m products
• reworking some of the applications content

[github-actions[bot]]

Developer checklist

• [x] Indicated the level of changes to this package by affixing one of these labels:
  • major -- Major changes to the API that may break current workflows
  • minor -- Minor changes to the API that do not break current workflows
  • patch -- Patches and bugfixes for the current version that do not break current workflows
  • bumpless -- Changes to documentation, CI/CD pipelines, etc. that don't affect the software's version
• [ ] ~(If applicable) Updated the dependencies and indicated any downstream changes that are required~
• [x] Added/updated documentation for these changes
• [ ] ~Added/updated tests for these changes~

Reviewer checklist

• [ ] ~Have all dependencies been updated?~
• [x] Is the level of changes labeled appropriately?
• [x] Are all the changes described appropriately in CHANGELOG.md?
• [x] Has the documentation been adequately updated?
• [ ] ~Are the tests adequate?~