Fix headings in tutorials

[acocac]

The PR fixes mainly heading levels in notebooks. Other changes:

• Add a new section to load/import libraries
• Capitalise all section names
• Remove question mark in the sentence indicating coordinates are in bold.
• Fix minor typos

[keewis]

Thanks, @acocac. Really minor, but would it be possible to rename Load libraries to Import libraries? I think that's the more common term in python.

[keewis]

looks like there's an issue with setup-micromamba. This is a docs-only PR, though, so I'm going to go ahead an merge anyways. Thanks again, @acocac!