Fix inconsistent markdown formatting.

This changes all of the documentation markdown files to follow
the same rules. The rules I've applied are from
https://github.com/DavidAnson/markdownlint/blob/v0.25.1/doc/Rules.md

The reason I felt it was necessary
to change all the files was
that there were a lot inconsistencies in how the markdown was used.
Ranging from header levels to some headers having a new line before
content and some not.

docs/readme.md

@@ -1,13 +1,15 @@
-![Dashy Docs](https://i.ibb.co/4mdNf7M/heading-docs.png)
+# ![Dashy Docs](https://i.ibb.co/4mdNf7M/heading-docs.png)
+
+## Running Dashy
 
-### Running Dashy
 - [Quick Start](/docs/quick-start.md) - TLDR guide on getting Dashy up and running
 - [Deployment](/docs/deployment.md) - Full guide on deploying Dashy either locally or online
 - [Configuring](/docs/configuring.md) - Complete list of all available options in the config file
 - [App Management](/docs/management.md) - Managing your app, updating, security, web server configuration, etc
 - [Troubleshooting](/docs/troubleshooting.md) - Common errors and problems, and how to fix them
 
-### Development and Contributing
+## Development and Contributing
+
 - [Developing](/docs/developing.md) - Running Dashy development server locally, and general workflow
 - [Development Guides](/docs/development-guides.md) - Common development tasks, to help new contributors
 - [Contributing](/docs/contributing.md) - How you can help keep Dashy alive
@@ -15,7 +17,8 @@
 - [Credits](/docs/credits.md) - List of people and projects that have made Dashy possible
 - [Release Workflow](/docs/release-workflow.md) - Info about releases, CI and automated tasks
 
-### Feature Docs
+## Feature Docs
+
 - [Authentication](/docs/authentication.md) - Guide to setting up authentication to protect your dashboard
 - [Alternate Views](/docs/alternate-views.md) - Outline of available pages / views and item opening methods
 - [Backup & Restore](/docs/backup-restore.md) - Guide to backing up config with Dashy's cloud sync feature
@@ -27,7 +30,8 @@
 - [Theming](/docs/theming.md) - Complete guide to applying, writing and modifying themes + styles
 - [Widgets](/docs/widgets.md) - List of all dynamic content widgets, with usage guides and examples
 
-### Misc
+## Misc
+
 - [Privacy & Security](/docs/privacy.md) - List of requests, potential issues, and security resources
 - [License](/LICENSE) - Copy of the MIT License
 - [Legal](/.github/LEGAL.md) - Licenses of direct dependencies