Merge pull request #1781 from laf/docs1

Added docs for device groups and tried to make sure old alerting docs are clear

doc/Extensions/Device-Groups.md

@@ -0,0 +1,30 @@
+# Device Groups
+
+LibreNMS supports grouping your devices together in much the same way as you can configure alerts. This document will hopefully help you get started.
+
+### Pattern
+
+Patterns work in the same was as Entities within the alerting system, the format of the pattern is based on the MySQL structure your data is in such 
+as __tablename.columnname__. If you are ensure of what the entity is you want then have a browse around inside MySQL using `show tables` and `desc <tablename>`.
+
+As a working example and a common question, let's assume you want to group devices by hostname. If you hostname format is dcX.[devicetype].example.com. You would use the pattern 
+devices.hostname. Select the condition which in this case would Like and then enter [email protected]. This would then match dc1.sw01.example.com, dc1.rtr01.example.com but not
+ dc2.sw01.example.com.
+
+#### Wildcards
+
+As used in the example above, wildcards are represented by the @ symbol. I.e @.example.com would match any hostnames under example.com.
+
+A list of common entities is maintained in our [Alerting docs](http://docs.librenms.org/Extensions/Alerting/#entities).
+
+### Conditions
+
+Please see our [Alerting docs](http://docs.librenms.org/Extensions/Alerting/#syntax) for explanations.
+
+### Connection
+
+If you only want to group based on one pattern then select And. If however you want to build a group based on multiple patterns then you can build a SQL like 
+query using And / Or. As an example, we want to base our group on the devices hostname AND it's type. Use the pattern as before, devices.hostname, select the condition which in this case would Like and then enter [email protected] then click And. Now enter devices.type in the pattern, select Equals and enter firewall. This would then match dc1.fw01.example.com but not dc1.sw01.example.com as that is a network type.
+
+You can now select this group from the Devices -> All Devices link in the navigation at the top. You can also use the group to map alert rules to by creating an alert mapping 
+Overview -> Alerts -> Rule Mapping.

doc/Extensions/Email-Alerting.md

@@ -2,7 +2,10 @@
 
 #### Please see [The new alerting docs](http://docs.librenms.org/Extensions/Alerting/#transports-email)
 
-Currently, the email alerts needs to be set up in the config. If you want to enable it, paste this in your config and change it:
+> None of these configuration options will work on builds older than the 1st of August 2015.
+
+
+~~Currently, the email alerts needs to be set up in the config. If you want to enable it, paste this in your config and change it:~~
 
 ```php
 // Mailer backend Settings