update iPad docs to reflect info in Sep 2021

[bpmct]

This updates our iPad.md docs to reflect some of the latest changes I observed when using code-server on an iPad.

• Mention the scrolling issue (Can’t scroll on iPad with a trackpad. #1455) has been fixed
• Add the terminal text issue (3.11 - Terminal not properly visible on iPad #3824) under known issues
• Add lose focus issue (iPad pro editor lose focus after swipping back from safari browser #4182) under known issues

I also moved the self-signed certificate instructions towards the bottom of the docs since it is not something we recommend.

[github-actions]

✨ Coder.com for PR #4228 deployed! It will be updated on every commit.

• Host: https://codercom-h07347wmf-codercom.vercel.app/docs/code-server
• Last deploy status: success
• Commit: ee04915
• Workflow status: https://github.com/cdr/code-server/actions/runs/1266292058

[codecov]

Codecov Report

Merging #4228 (a9b41dd) into main (e8063c7) will not change coverage.
The diff coverage is n/a.

❗ Current head a9b41dd differs from pull request most recent head ee04915. Consider uploading reports for the commit ee04915 to get more accurate results

@@           Coverage Diff           @@
##             main    #4228   +/-   ##
=======================================
  Coverage   65.09%   65.09%           
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  Files          36       36           
  Lines        1882     1882           
  Branches      380      380           
=======================================
  Hits         1225     1225           
  Misses        559      559           
  Partials       98       98           

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[jsjoeio]

Awesome! Thanks for doing this Ben 🚀