Update theme to use repo since gem is forcing old version of Jekyll which breaks Github Pages build

Author: hilary-luo

Gemfile

@@ -1,7 +1,5 @@
 source "https://rubygems.org"
 
-gem "jekyll-rtd-theme", "~> 2.0.10"
-
 group :jekyll_plugins do
     gem "github-pages"
     gem "jekyll-tabs"

_config.yml

@@ -2,9 +2,11 @@ title: User Manual
 lang: en
 description: Turtlebot4 User Manual
 repository: turtlebot/turtlebot4-user-manual
+domain: turtlebot.github.io
+url: https://turtlebot.github.io
 baseurl: /turtlebot4-user-manual
 
-remote_theme: rundocs/jekyll-rtd-theme
+remote_theme: clearpathrobotics/jekyll-rtd-theme
 
 readme_index:
   with_frontmatter: true
@@ -23,3 +25,4 @@ plugins:
   - jekyll-avatar
   - jekyll-mentions
   - jekyll-tabs
+  - jekyll-remote-theme