Improve Docker documentation in the repo

Now it will link to the wiki too.

docs/cryptpad-docker.md

@@ -1,5 +1,11 @@
 # Cryptpad Docker Image
 
+Cryptpad includes support for building a Docker image and running it to provide a Cryptpad instance. You can manage the container manually, or let Docker Compose manage it for you.
+
+A full tutorial is available [on the Cryptpad Github wiki](https://github.com/xwiki-labs/cryptpad/wiki/Docker-(with-Nginx-and-Traefik)). This document provides a brief overview.
+
+## Features
+
 - Configuration via .env file
 - Ready for use with traffic
 - Using github master for now, release 0.3.0 too old
@@ -9,14 +15,22 @@
 
 ## Run
 
-Run from the cryptpad source directory:
+Run from the cryptpad source directory, keeping instance state in `/var/cryptpad`:
 
 ```
 docker build -t xwiki/cryptpad .
-docker run --restart=always -d --name cryptpad -p 3000:3000 -v /var/cryptpad:/cryptpad/datastore xwiki/cryptpad
+docker run --restart=always -d --name cryptpad -p 3000:3000 \
+-v /var/cryptpad/files:/cryptpad/datastore \
+-v /var/cryptpad/customize:/cryptpad/customize 
+-v /var/cryptpad/blob:/cryptpad/blob \
+-v /var/cryptpad/blobstage:/cryptpad/blobstage \
+-v /var/cryptpad/pins:/cryptpad/pins \
+-v /var/cryptpad/tasks:/cryptpad/tasks \
+-v /var/cryptpad/block:/cryptpad/block \ 
+xwiki/cryptpad
 ```
 
-Or, using docker-compose
+Or, using docker-compose and the included `docker-compose.yml`, keeping instance state in the current directory under `./data`:
 
 ```
 docker-compose up -d
@@ -39,10 +53,15 @@ On runtime, in `bin/container-start.sh` the settings are written to the `config.
 
 The docker-compose file is preconfigured to persist folders
 
-- cryptpad/datastore --> ./data/customize
+- cryptpad/datastore --> ./data/files
 - cryptpad/customize --> ./data/customize
+- cryptpad/pins --> ./data/pins
+- cryptpad/blob --> ./data/blob
+- cryptpad/blobstage --> ./data/blobstage
+- cryptpad/tasks --> ./data/tasks
+- cryptpad/block --> ./data/block
 
-In customize included find your configuration in `config.js`.
+Your configuration file will be in `./data/customize/config.js`.
 
 The data folder is ignored by git, so if you want to add your customizations to git versioning change the volume: