Add a documentation section for prerequisite knowledge required to use jrnl

[micahellison]

Affected Page(s)

https://jrnl.sh/en/stable/usage/

What Could Be Better?

We have a few "note" sections about how the specifics of terminal usage affect jrnl, such as mentioning reserved characters' effect on commands. It could be nice to have a section on the specific terminal skills needed to make jrnl work well. Then these notes could be condensed and a link to this section could be added to them.

We don't necessarily have to go into a detail about all these skills, but listing them and linking to related resources could help.

Here's a start:

• what a terminal is
• how to run commands with arguments
• reserved characters on a terminal
• configuration files
• piping
• stdout vs stderr

Other Information

Relates to #1768 but is a much larger scope.