More docs fixes

1. Set paragraph size to 80 chars for better readability.
2. More formatting fixes.
3. More spelling and grammar fixes.

docs/sources/installation/docker.md

@@ -8,27 +8,31 @@ page_keywords: grafana, installation, docker, container, guide
 
 ## Install from offical docker image
 
-Grafana has an offical docker container.
+Grafana has an official Docker container.
 
     $ docker run -i -p 3000:3000 grafana/grafana
 
-All grafana configuration settings can be defined using ENVIRONMENT variables, this is especially useful when using the
-above container.
+All Grafana configuration settings can be defined using environment
+variables, this is especially useful when using the above container.
 
 ## Docker volumes & ENV config
 
-The docker container exposes two volumes, the sqlite3 database in the folder `/var/lib/grafana` and
-configuration files is in `/etc/grafana/` folder. You can map these volumes to host folders when you start the container:
+The Docker container exposes two volumes, the sqlite3 database in the
+folder `/var/lib/grafana` and configuration files is in `/etc/grafana/`
+folder. You can map these volumes to host folders when you start the
+container:
 
     $ docker run -d -p 3000:3000 \
         -v /var/lib/grafana:/var/lib/grafana \
         -e "GF_SECURITY_ADMIN_PASSWORD=secret  \
         grafana/grafana:develop
 
-In the above example I map the data folder and set a config option via an `ENV` variable.
+In the above example I map the data folder and sets a configuration option via
+an `ENV` instruction.
 
 ## Configuration
 
-The backend web server has a number of configuration options. Go the [Configuration](/installation/configuration) page for details
-on all those options.
+The back-end web server has a number of configuration options. Go the
+[Configuration](/installation/configuration) page for details on all
+those options.