Create markdown.md, fixes #17

Author: caendesilva

markdown.md

@@ -0,0 +1,61 @@
+---
+---
+
+# Markdown with Hyde
+
+Hyde makes heavy use of Markdown. While this page won't teach you how to use Markdown,
+it will hopefully shed some light about how Hyde uses it, and how you can extend it using Front Matter.
+
+## Front Matter
+
+All Markdown content files support Front Matter. Blog posts for example make heavy use of it.
+
+The specific usage and schemas used for pages are documented in their respective documentation,
+however, here is a primer on the fundamentals.
+
+- Front matter is stored in a block of YAML that starts and ends with a `---` line.
+- The front matter should be the very first thing in the Markdown file.
+- Each key-pair value should be on its own line.
+
+**Example:**
+```markdown
+---
+title: "My New Post"
+author:
+  name: "John Doe"
+  website: https://mrhyde.example.com
+---
+
+## Markdown comes here
+
+Lorem ipsum dolor sit amet, etc.
+```
+
+## CommonMark environment
+
+Hyde uses [League CommonMark](https://commonmark.thephpleague.com/) for converting Markdown into HTML.
+
+### Customizing the environment 
+
+Hyde ships with the Github Flavored Markdown extension, and 
+the Torchlight extension is enabled automatically when needed.
+
+You can add extra CommonMark extensions, or change the default ones, in the `config/markdown.php` file.
+
+```php
+'extensions' => [
+	\League\CommonMark\Extension\GithubFlavoredMarkdownExtension::class,
+	\League\CommonMark\Extension\Attributes\AttributesExtension::class,
+	\League\CommonMark\Extension\DisallowedRawHtml\DisallowedRawHtmlExtension::class,
+],
+```
+
+In the same file you can also change the config to be passed to the CommonMark environment.
+
+```php
+'config' => [
+	'disallowed_raw_html' => [
+		'disallowed_tags' => [],
+	],
+],
+```