dendron.guides.tips: replace shell alias with wrapper script & add linux desktop file

What does this PR do?

Replaces the shell alias setup in the Linux-specific section of dendron.guides.tips with a wrapper script so Dendron can be invoked from anywhere, not just a shell session, which is a prerequisite for the next point
Adds a section to dendron.guides.tips which showcases how to add Dendron to your launcher/desktop on Linux using a .desktop file
Apparently my VSCode setup has rather strong opinions about whitespace in markdown files which makes the first commit kind of messy. If you'd prefer having that reverted, let me know and I'll fix it.

For more information, visit the Contributing Guide for Documentation

[X] Check rendered output to ensure formatting is correct for renderings of wikilinks, note refs, tables, and images. Dendron: Show Preview can be used in your workspace to confirm the page renders as expected. Sometimes, Dendron: Reload Index needs to be ran if certain wikilinks aren't working as expected. (ignore this if contribution is made via the Edit this page on GitHub button from the published site)
[X] If this PR includes any refactoring (renaming notes, renaming headers, etc.), make sure that these changes were done via Dendron Refactoring Commands. This will ensure that any other impacted areas of the documentation, that link to or embed modified notes (via note references), are automatically updated.

Verify GitHub Actions tests are passing, which can be seen in the Checks tab of the PR:

NOTE: If you are a new contributor, a maintainer will need to provide approval for GitHub Actions to run on your PRs.