Add plugins configurations.

Notice that mathjax uses a CDN.
This is temporary.

user/config/plugins/anchors.yaml

+enabled: true
+active: true
+selectors: 'h1,h2,h3,h4,h5'
+placement: right
+visible: hover
+truncate: 64

user/config/plugins/git-sync.yaml

+enabled: false
+folders:
+  - pages
+sync:
+  on_save: false
+  on_delete: false
+  on_media: false
+  # cron_enabled (pls)
+  cron_enable: false
+  cron_at: '0 12,23 * * *'
+repository: 'https://m3p2.ljbac.com/m3p2/courses.git'
+user: Goutte
+password:
+webhook: /git-sync
+webhook_enabled: '0'
+webhook_secret:
+branch: master
+remote:
+  name: origin
+  branch: master
+git:
+  author: gituser
+  message: '(Grav GitSync) Automatic Commit'
+  name: GitSync
+  email: m3p2-bot@ljbac.com
+  bin: git
+logging: false

user/config/plugins/highlight.yaml

+enabled: true
+theme: default
+lines: false

user/config/plugins/language-selector.yaml

+enabled: true
+built_in_css: true
+untranslated_pages_behavior: none
+button_display: flag
+select_display: default

user/config/plugins/markdown-notices.yaml

+enabled: true
+built_in_css: true
+level_classes:
+  - blue
+  - green
+  - yellow
+  - red

user/config/plugins/mathjax.yaml

+enabled: true
+active: true
+built_in_css: true
+built_in_js: true
+weight: -5
+delimiters:
+  inline:
+    \(: \)
+    $: $
+  block:
+    '\[': '\]'
+    $$: $$
+CDN:
+  enabled: true
+  url: 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML'