various fixes

hooks/sentry/README.md

@@ -1,12 +1,15 @@
 # Sentry Hook for Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:" />
 
-[Sentry](https://getsentry.com) provides both self-hosted and hostes solutions for exception tracking.
-Both client and server are [open source](https://github.com/getsentry/sentry).
+[Sentry](https://getsentry.com) provides both self-hosted and hosted
+solutions for exception tracking.
+Both client and server are
+[open source](https://github.com/getsentry/sentry).
 
 ## Usage
 
-Every sentry application defined on the server gets a different [DNS](https://www.getsentry.com/docs/). In the example below replace `YOUR_DSN` with the one created for your application.
-
+Every sentry application defined on the server gets a different
+[DSN](https://www.getsentry.com/docs/). In the example below replace
+`YOUR_DSN` with the one created for your application.
 
 ```go
 import (
@@ -27,3 +30,13 @@ func main() {
   }
 }
 ```
+
+## Special fields
+
+Some logrus fields have a special meaning in this hook,
+these are server_name and logger.
+When logs are sent to sentry these fields are treated differently.
+- server_name (also known as hostname) is the name of the server which
+is logging the event (hostname.example.com)
+- logger is the part of the application which is logging the event.
+In go this usually means setting it to the name of the package.