FontAwesome 6 upgrade: followup items

[chalin]

Followup to:

• Upgrade to FontAwesome 6 #1102

Tasks:

• Search placeholder text font is in ALLCAPS #1169
• Use SCSS variable for FA font name #1170
• Mention the breaking change in the CHANGELOG
  • For a link to add, see Upgrade to FontAwesome 6 #1102 (comment).
  • Add FontAwesome change in changelog #1186
• Ensure Docsy via Hugo module still works after Font Awesome upgrade #1165
• Search icon (magnifying glass) is not rendered properly in FF #1256
• Update docsy theme to dosy version v0.5.1 docsy-example#188

[chalin]

@samiahmedsiddiqui - let me know if you'd like to tackle some of these tasks.

[samiahmedsiddiqui]

@chalin PR created for #1170, I will try to create a PR for #1169 tomorrow.

[chalin]

Wonderful! I think that for #1169, all we might need to do is change the order of the listed fonts (at least that was what I was going to try :).

[chalin]

@samiahmedsiddiqui - FYI, I've submitted a fix for #1169 via #1179.