docs: Add usage

Signed-off-by: Tim Hårek Andreassen <tim@harek.no>

README.md

@@ -1,5 +1,28 @@
-# yr-go
+# yr
 
-This is currently work in progress. My goal with this is to learn more Go and
-have a Go-package that I can use from met.no and hopefully a CLI tool to check
-the weather.
+Get the weather delivered to your command-line.
+
+## Usage
+
+```bash
+# Get help
+yr --help
+
+# Current forecast for location
+yr now bergen
+
+# Or with a space
+yr now "new york"
+
+# Forecast for multiple hours
+yr forecast "new york"
+
+# Forecast for next 5 hours
+yr forecast "new york" -i 5
+
+# Open forecast in your web browser
+yr forecast "new york" --web
+
+# Open now in your web browser
+yr now "new york" --web
+```