Document the new launch action

docs/launch.rst

@@ -4,6 +4,38 @@ Launching programs in new windows/tabs
 .. program:: launch
 
 
+|kitty| has a :code:`launch` action that can be used to run arbitrary programs
+in news windows/tabs. It can be mapped to user defined shortcuts in kitty.conf.
+It is very powerful and allows sending the contents of
+the current window to the launched program, as well as many other options.
+
+In the simplest form, you can use it to open a new kitty window running the
+shell, as shown below::
+
+    map f1 launch
+
+To run a different program simply pass the command line as arguments to
+launch::
+
+    map f1 launch vim path/to/some/file
+
+
+To open a new window with the same working directory as the currently
+active window::
+
+    map f1 launch --cwd=current
+
+To open the new window in a new tab::
+
+    map f1 launch --type=tab
+
+To pass the contents of the current screen and scrollback to the started process::
+
+    map f1 launch --stdin-source=@screen_scrollback less
+
+There are many more powerful options, refer to the complete list below.
+
+
 Syntax reference
 ------------------