docs(linux): add guide for discord audio

[RickAndTired]

Description

Linux Guide - How to not stream Discord call audio

Notes

I wasn't sure how to handle the images, so I placed them here:
docs/source/about/guides/linux/discord_calls/

The images are linked to my fork and should be updated to the official LizardByte repo if this PR is merged

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

Branch Updates

LizardByte requires that branches be up-to-date before merging. This means that after any PR is merged, this branch
must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

[CLAassistant]

All committers have signed the CLA.

[ReenigneArcher]

Can you place the images in ./docs/source/images?

I've also made some suggestions for having the steps in a numbered list.

[RickAndTired]

Can you place the images in ./docs/source/images?

I've also made some suggestions for having the steps in a numbered list.

I moved the images to the requested directory
I included the numbered list
(I had tried bullet points because the numbers were being reset by the images, I didn't notice the indented images fixed that)

[ReenigneArcher]

Thanks! A few more small adjustments needed.

You can see the preview here: https://lizardbyte--2447.org.readthedocs.build/projects/sunshine/en/2447/about/guides/linux/discord_calls.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 6.77%. Comparing base (50a02db) to head (4a608f2).

Additional details and impacted files

@@           Coverage Diff            @@
##           nightly   #2447    +/-   ##
========================================
  Coverage     6.77%   6.77%            
========================================
  Files           86      86            
  Lines        17523   17523            
  Branches      8134    8015   -119     
========================================
  Hits          1187    1187            
+ Misses       15444   15396    -48     
- Partials       892     940    +48     

Flag	Coverage Δ
Linux	5.75% <ø> (ø)
Windows	2.04% <ø> (ø)
macOS-12	8.44% <ø> (-0.13%)	⬇️
macOS-13	7.78% <ø> (ø)
macOS-14	8.11% <ø> (ø)

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see 16 files with indirect coverage changes