docs: Main docs update (#1304)

* Remove template in favor of official samples

* Fixed a variable name copy pasta mistake

line 35 was _database.GetData() instead of DBService.GetData()

* Experimental theme change

* Change paragraph, code, heading fonts
* Widen viewport

* Update DocFX.Plugins.LastModified v1.2.3

* Exclude Discord.API in docs

* Add remarks for SocketReaction properties

* Add examples for BaseSocketClient.Events

* Add additional clarification for some methods

* Move IUser and IGuildChannel examples

* Clarify several guides samples with notes

- Reword TypeReader comment to avoid giving the idea that the sample itself is "obsolete"
- Remove CommandException logging comment regarding C#7.0 as the version is now the standard across VS2017 and up
- Remove suggestion about handling result in command handler since it is now advised to use CommandExecuted instead
+ Add additional comment to clarify ctor for DI setup

* Add/migrate code examples

* Incorporate material design theme

License @ https://github.com/ovasquez

* Update installation and nightly guide

* Fix improper indentations made obvious by the widen viewport
* Fix minor grammar issues
+ Add installation for nightly build using dotnet CLI

* Fix nav level indentation

* Revise "Your First Bot" article

* Merge some paragraphs to avoid clutter while keeping readability
* Reword the use of command framework
+ Add additional warning/note about environment variable

* Add additional indent level

* Fix indentation text warping

* Remove connections sample

* Update logging sample

Remove redundant part of the sample

* Remove mention of RPC

* Remove misleading section about commands

- Remove command sample from complete snippet
* Revise "Your First Bot" command paragraphs
* Change wording to hint devs that additional command parser packages may be available, as more and more begin to crop up

* Update themes

* Add XML docs contribution guidelines


Update guidelines

* Update CommandExecuted remarks

* Fix precondition remarks typo
no one saw that ok

* Fix permission sample in docfx

* Fix IMessageChannel samples

* Update docs/_template/light-dark-theme/styles/docfx.vendor.minify.css

Co-Authored-By: Still34 <341464@gmail.com>

* Update docs/_template/light-dark-theme/styles/material.css

Co-Authored-By: Still34 <341464@gmail.com>

* Update docs/_template/light-dark-theme/styles/material.css

Co-Authored-By: Still34 <341464@gmail.com>

docs/_template/light-dark-theme/styles/master.css

@@ -1,14 +1,37 @@
-@import url('https://fonts.googleapis.com/css?family=Titillium+Web|Noto+Sans');
+@import url('https://fonts.googleapis.com/css?family=Roboto|Muli|Fira+Mono');
 
 html,
 body {
-    font-family: 'Titillium Web', 'Segoe UI', Tahoma, Helvetica, sans-serif;
+    font-family: 'Roboto', 'Segoe UI', Tahoma, Helvetica, sans-serif;
     font-display: optional;
     height: 100%;
     font-size: 15px;
     scroll-behavior: smooth;
 }
 
+code{
+    font-family: 'Fira Mono', 'Courier New', Courier, monospace
+}
+
+h1,
+h2,
+h3,
+h4,
+h5,
+h6 {
+    font-family: 'Muli', Verdana, Geneva, Tahoma, sans-serif;
+    line-height: 130%;
+}
+
+h1,
+.h1,
+h2,
+.h2,
+h3,
+.h3 {
+  font-weight: 600;
+}
+
 #logo
 {
     max-width: 100px;
@@ -25,6 +48,14 @@ li,
     line-height: 160%;
 }
 
+.toc-filter{
+    background: inherit !important;
+}
+
+.affix ul>li.active>ul, .affix ul>li.active>a:before, .affix ul>li>a:hover:before{
+    white-space: normal;
+}
+
 img {
     box-shadow: 0px 0px 3px 0px rgb(66, 66, 66);
     max-width: 95% !important;
@@ -57,16 +88,6 @@ article.content h6{
     transition: all .25s ease-in-out;
 }
 
-h1,
-h2,
-h3,
-h4,
-h5,
-h6 {
-    font-family: 'Noto Sans', Verdana, Geneva, Tahoma, sans-serif;
-    line-height: 130%;
-}
-
 .sideaffix {
     line-height: 140%;
 }
@@ -173,3 +194,38 @@ span.arrow-d{
 span.arrow-r{
     top: 6px; position: relative;
 }
+
+/* widen viewport */
+
+@media (min-width: 1085px) {
+    .container {
+        width: calc(100% - 15vw);
+        max-width: calc(100% - 15vw);
+    }
+}
+
+/* fix level indentation */
+
+.level2 {
+    padding: 0 5px;
+}
+
+.level3 {
+    padding: 0 5px;
+    font-size: 90%;
+}
+
+.level4 {
+    padding: 0 5px;
+    font-size: 85%;
+}
+
+.level5 {
+    padding: 0 5px;
+    font-size: 80%;
+}
+
+.level6 {
+    padding: 0 5px;
+    font-size: 75%;
+}