Cross compile and README update

README.md

@@ -1,2 +1,28 @@
 # rtl-gopow
 Render tables from rtl_power to a nice heat map
+Here is an render of rtl_power tool scanning 80-90 MHz during 2.5 hours moving in a car. ![80-90 MHz](http://i.imgur.com/knkzLXO.jpg).
+
+# Availability
+Since Go is easy to cross compile, this tool can be easily distributed as a binary without any dependencies. You'll find it under Releases here on github. The following platforms are avalible as a ready to run binary file:
+
+* OS X (x64)
+* Linux (x64)
+* Linux (arm5)
+* Linux (arm7)
+* Windows (x64)
+
+## Performance
+A render of a 600 MB csv file takes about 2 minutes on a 2,4 GHz Intel Core i5. There is still lots of room for improvement on that though. Memory usage is quite horrid.
+
+## Options
+```
+GLOBAL OPTIONS:
+   --input, -i      CSV input file generated by rtl_power [required]
+   --output, -o     Output file, default same as input file with new extension
+   --format, -f 'png'   Output file format, default png [png,jpeg]
+   --verbose        Enable more verbose output
+   --no-annotations Disabled annotations such as time and frequency scales
+   --help, -h       show help
+   --version, -v    print the version
+
+   ```