[docs] big bang update (#348)

* [docs] big bang update

* Simplified polluted README.md by moving parts to the documentation
* Removed duplicates with `pymdownx.snippets` extension
* Enabled code copy
* Extended "Getting Started"
* Added "Monitoring" page
* Separated "Upgrade" page
* Added default config yaml to docs

Signed-off-by: Dmytro Bondar <git@bonddim.dev>

* Update sources.md

Co-authored-by: h44z <christoph.h@sprinternet.at>

---------

Signed-off-by: Dmytro Bondar <git@bonddim.dev>
Co-authored-by: h44z <christoph.h@sprinternet.at>

docs/documentation/overview.md

@@ -1,29 +1 @@
-**WireGuard Portal** is a simple, web based configuration portal for [WireGuard](https://wireguard.com).
-The portal uses the WireGuard [wgctrl](https://github.com/WireGuard/wgctrl-go) library to manage existing VPN
-interfaces. This allows for seamless activation or deactivation of new users, without disturbing existing VPN
-connections.
-
-The configuration portal supports using a database (SQLite, MySQL, MsSQL or Postgres), OAuth or LDAP 
-(Active Directory or OpenLDAP) as a user source for authentication and profile data.
-
-## Features
-* Self-hosted - the whole application is a single binary
-* Responsive web UI written in Vue.JS
-* Automatically select IP from the network pool assigned to client
-* QR-Code for convenient mobile client configuration
-* Sent email to client with QR-code and client config
-* Enable / Disable clients seamlessly
-* Generation of wg-quick configuration file (`wgX.conf`) if required
-* User authentication (database, OAuth or LDAP)
-* IPv6 ready
-* Docker ready
-* Can be used with existing WireGuard setups
-* Support for multiple WireGuard interfaces
-* Peer Expiry Feature
-* Handle route and DNS settings like wg-quick does
-* REST API for management and client deployment
-
-## Quick-Start
-
-The easiest way to get started is to use the provided [Docker image](./getting-started/docker.md).
-
+--8<-- "README.md:20:47"