Separate out reference documentation for command line arguments and config file

[micahellison]

Documentation Change

jrnl's documentation is somewhat incomplete but also a bit inconsistent in its approach. We get a fair amount of issues that I think are more about the problems with the docs than the program itself.

Lots of mature software projects tend to divide up documentation into four main areas:

• Tutorials - "getting started" and other quick introductions to the app with a little bit of context
• Topic guides - meant to help the user get an overall understanding of the concepts behind the application
• Reference guides - granular, technical reference
• How-to-guides - our recipes section

I think we've done a good job on tutorials, but we've kind of mixed up the other three categories. In particular, some of our documentation seems to be trying to be both tutorial and reference at the same time and I think that hurts its ability to meet either need.

At the very least, we should add:

• a reference guide for jrnl's arguments
• a reference guide for jrnl's config file keys

Once those two are added, we should rework the rest of the documentation that addresses arguments and the config file as necessary.

Affected Page(s)

• https://jrnl.sh/en/stable/formats/ doesn't seem to know if it's reference or how-to
• https://jrnl.sh/en/stable/advanced/ is a mish-mash of various topics that would be best split up
• A new argument reference guide
• A new config reference guide

Other Information

This piece on four types of documentation helped orient me towards this approach.

[micahellison]

When this issue is complete, I think it will resolve #995 as well.