Describe build process

Building-from-source.md

@@ -0,0 +1,16 @@
+```sh
+# Clone telegraf to your GOPATH (incl. all plugins/dependencies)
+go get -u github.com/influxdb/telegraf/...
+cd $GOPATH/src/github.com/influxdb/telegraph
+
+# Build binaries to the pkg/ directory
+./release.sh
+```
+
+This will currently build binaries for the following OS/architectures:
+
+- **linux/amd64**
+- **linux/386**
+- **darwin/amd64**
+
+NOTE: **linux/arm** support: [hopefully coming soon](https://github.com/influxdb/telegraf/pull/14), but very easily added on your own.