Improve documantion of many plugins

Specifically the configuration examples are now indented properly.

plugins/disk/btrfs_device_stats

@@ -13,8 +13,8 @@ btrfs_device_stats - Script to monitor btrfs device statistics
 Simply create a symlink in your plugins directory like with any other plugin.
 Must be run as root.
 
-[btrfs_device_stats]
-user root
+ [btrfs_device_stats]
+ user root
 
 =head2 DEFAULT CONFIGURATION
 

plugins/disk/btrfs_device_usage

@@ -13,8 +13,8 @@ btrfs_device_usage - Script to monitor usage of btrfs devices
 Simply create a symlink in your plugins directory like with any other plugin.
 Must be run as root.
 
-[btrfs_device_usage]
-user root
+ [btrfs_device_usage]
+ user root
 
 =head2 DEFAULT CONFIGURATION
 

plugins/disk/btrfs_subvol_usage

@@ -8,9 +8,9 @@ btrfs_subvol_usage - Plugin to monitor usage of BTRFS subvolumes
 
 Must be run as root and you have to specify the path to the filesystem
 
-[btrfs_usage]
-user root
-env.fsroot /path/to/btrfs/filesystem
+ [btrfs_usage]
+ user root
+ env.fsroot /path/to/btrfs/filesystem
 
 =head1 MAGIC MARKERS
 

plugins/disk/e2

@@ -8,8 +8,8 @@ ext2 - Wildcard plugin shows ext2/3/4 filesystem information (mount count, last
 
 =head1 CONFIGURATION
 
-[ext2_*]
-group disk,floppy
+ [ext2_*]
+ group disk,floppy
 
 =head1 AUTHOR
 

plugins/disk/file_age

@@ -88,7 +88,7 @@ file_age - Monitors the age of files.
 
 Since there is no way for the plugin to guess which files you want monitored, you're going to have to set each file up separately. Put the following in a file in your plugin-conf.d directory.
 
-[file_age]
+    [file_age]
     user root						# May not be necessary, depending on which files you want monitored.
 
     env.file1_path		/var/log/syslog		# Mandatory, complete path to file.