Add USAGE.md

Add link in README.md

Author: Clement Champetier

README.md

@@ -21,6 +21,11 @@ License
 See [**COPYING.md**](COPYING.md)
 
 
+How to use
+-------
+See [**USAGE.md**](USAGE.md)
+
+
 Compilation
 -----------
 Getting the source

USAGE.md

@@ -0,0 +1,28 @@
+# TuttleOFX
+
+This bunch of tools includes:
+* a set of command line tools called Sam,
+* some plugins like classical Resize, Lut, Crop... or LensDistort and Histogram Keyer.
+
+TuttleOFX plugins are based on OpenFX standard, making them usable with the Sam command line tool but also with other applications like Nuke (The Foundry), Scratch (Assimilate), Baselight (FilmLight), Mistika (SGO).
+
+## Sam
+
+Additionnal dependencies:
+
+* __clint__
+
+Clint is a module filled with a set of awesome tools for developing commandline applications.
+
+https://pypi.python.org/pypi/clint/ <br/>
+Suggested version: v0.4.1
+
+* __argcomplete__
+
+Argcomplete provides easy, extensible command line tab completion of arguments for your Python script.
+
+https://pypi.python.org/pypi/argcomplete <br/>
+Suggested version: v0.9.0
+
+## More information
+http://www.tuttleofx.org/user-documentation