Some small docs improvements

docs/docs/development.rst

@@ -8,6 +8,8 @@ Jedi Development
 .. note:: This documentation is for Jedi developers who want to improve Jedi
     itself, but have no idea how Jedi works. If you want to use Jedi for 
     your IDE, look at the `plugin api <api.html>`_.
+    It is also important to note that it's a pretty old version and some things
+    might not apply anymore.
 
 
 Introduction

docs/docs/installation.rst

@@ -11,8 +11,16 @@ jedi-vim_ does by default), or you can install it systemwide.
     editor, refer to the corresponding documentation.
 
 
-The preferred way
+The normal way
------------------
+--------------
+
+Most people use Jedi with a :ref:`editor plugins<editor-plugins>`. Typically
+you install Jedi by installing an editor plugin. No necessary steps are needed.
+Just take a look at the instructions for the plugin.
+
+
+With pip
+--------
 
 On any system you can install |jedi| directly from the Python package index
 using pip::

jedi/api/classes.py

@@ -329,7 +329,7 @@ class BaseDefinition(object):
     @memoize_method
     def params(self):
         """
-        Raises an ``AttributeError``if the definition is not callable.
+        Raises an ``AttributeError`` if the definition is not callable.
         Otherwise returns a list of `Definition` that represents the params.
         """
         # Only return the first one. There might be multiple one, especially