Complete Readthedocs and generate users manual

[Klankers]

Readthedocs is great for also going into better detail on a number of things related to CTDCAL. More brainstorming is required, but the following could be included:

• How to install (improving what we already have)
• Getting started
• How to build your own workflow from modular pieces
• Sensors supported
• Troubleshooting (this can be as broad or as specific as we want)

At the end, we want to be able to generate a single manual from Readthedocs in a manner similar to that of Sphinx cruise reports. A single PDF that users can take with them into the field or refer to for use on other devices without needing the internet.

[Klankers]

It's worth noting that a user's manual PDF could be automatically generated from Readthedocs. Keeping everything formatted correctly, with correct PDF support, should generate something nice. https://ctdcal.readthedocs.io/_/downloads/en/latest/pdf/