midi2osc/LV3: Faderfox LV3 mappings (work in progress)

Also added section titles in README and a section on loading mappings
from files.

midi2osc/README

@@ -1,3 +1,6 @@
+midi2osc - MIDI to OSC forwarder
+================================
+
 midi2osc register itself as a writeable MIDI device. It then forwards
 the MIDI messages it receives to the specified OSC destination.
 
@@ -10,6 +13,10 @@ Compilation:
 
 make
 
+
+Usage
+-----
+
 To use it with the Milkymist One,
 
 - enable Ethernet on the M1
@@ -36,3 +43,12 @@ a host called "m1".
 If <value> is given, that value will be assigned for any control
 message that matches the input pattern, irrespective of the input
 value.
+
+
+File-based mappings
+-------------------
+
+To load mappings from a file containing #-style comments, the
+following invocation can be used:
+
+midi2osc `sed 's/#.*//' filename` ...