Display Persian (`fa`) pages in right-to-left (RTL) fashion & other improvements

[chalin]

• Specify fa as rtl lang + NPM script tweak #294
• Upgrade Docsy to include RTL support + tweak fa config #300
• [fa] Ensure that at least one page has a sidenav and TOC #302
• Upgrade Docsy to v0.10.0-11-g6549143 #304
• Upgrade Docsy to v0.10.0-12-g333c2f8 #305 - brings in RTL support for projects using Docsy via Hugo modules
• Upgrade Docsy to v0.10.0-33-gfe0d785, add rtlcss pkg #322
• [i18n] Ensure that "Learn more" of non-en index links to same-language docs #325
• [fa] Add remaining i18n entries docsy#2019
• Upgrade Docsy

[theletterf]

It'd be nice to see an example of a full sidebar, with a ToC and other elements, like here: https://www.docsy.dev/docs