docs: add section on correctly configuring fonts / priority etc

[goyalyashpal]

Description

A description of the change, what it does, and why it was made. If relevant (such as any change that modifies the UI), please provide screenshots of the changes:

• Change: docs: add section on correctly configuring fonts / priority etc
• Why: So that graph points (braille) is rendered correctly / as-expected

Issue

If applicable, what issue does this address?

Closes: #1694

Testing

If relevant, please state how this was tested. All changes must be tested to work:

If this is a code change, please also indicate which platforms were tested:

• Windows
• macOS
• Linux

Checklist

If relevant, ensure the following have been met:

• Areas your change affects have been linted using rustfmt (cargo fmt)
• The change has been tested and doesn't appear to cause any unintended breakage
• Documentation has been added/updated if needed (README.md, help menu, doc pages, etc.)
• The pull request passes the provided CI pipeline
• There are no merge conflicts
• If relevant, new tests were added (don't worry too much about coverage)

[goyalyashpal]

.

• destination: troubleshooting at pages.dev (see: #1703)
  (or the current-but-old troubleshooting at gh.io)
• files: content/troubleshooting.md
• discussion

.

• contribution guidelines: documentation contribution
• commit message reference: commit history
• no documentation style guide found
• no pattern for line-breaks (char limit, or sentence breaks) observed

so,

• for the portions i will be adding, i will make them in ventilated prose (i.e. one sentence per line)
• stick with inline links (already used exclusively) as they're self-contained, hence easy to move around
  i will see if using reference links seems to fit here. otherwise, i will use inline ones too.
• i will (try) to not make any style change (like listed above) to unrelated portions, and keep these to minimum to sorrounding lines.

[goyalyashpal]

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