[sphinx] Clean up

doc/guide.rst

@@ -18,16 +18,10 @@
 
 
 
-==============================
- Linear Machines and Trainers
-==============================
-
-Machines are one of the core components of |project|. They represent
-statistical models or other functions defined by parameters that can be learnt
-or manually set. The simplest of |project|'s machines is a
-:py:class:`bob.learn.linear.Machine`. This package contains the definition of
-this class as well as trainers that can learn linear machine parameters from
-data.
+==================
+ Linear Estimators
+==================
+
 
    
 Whitening