Typos, clarification of documentation.

doc/extending/graphstructures.txt

@@ -376,26 +376,27 @@ of inputs.  In fact, doing so will raise an exception.
 Graph Structures Extension
 ==========================
 
-When we start the compilation of a Theano funciton, we compute extra
-information that is available to you.. This section try to describe
-them. Not all are described up to now, so if you miss something, email
-theano-dev.
+When we start the compilation of a Theano function, we compute some
+extra information. This section describes a portion of the information
+that is made available. Not everything is described, so email
+theano-dev if you need something that is missing.
 
-The graph get cloned at the start of compilation, so modificatio done
+
+The graph gets cloned at the start of compilation, so modifications done
 during compilation won't affect the user graph.
 
-Each variable receive a new field called clients. It is a list with
-`pointors` to every place in the graph where this variable is used. If
-its length is 0, it mean the variable isn't used. Each place where it
-is used are described as a tuple of 2 elements. There is two type of
+Each variable receives a new field called clients. It is a list with
+reference to every place in the graph where this variable is used. If
+its length is 0, it means the variable isn't used. Each place where it
+is used is described by a tuple of 2 elements. There is two types of
 pairs:
 
 - The first element is an Apply node.
-- The first element is the string "output". It mean the theano
-  function output this variable.
+- The first element is the string "output". It means the
+  function outputs this variable.
 
-In all type of pairs, the second element of the tuple is an index,
-such that: ``the_apply_node.inputs[index]`` or
+In both types of pairs, the second element of the tuple is an index,
+such that: ``var.clients[*][0].inputs[index]`` or
 ``fgraph.outputs[index]`` is that variable.
 
 .. code-block:: python