[3.0.x] Corrected some typos in documentation.

Backport of 70d95682b1 from master

docs/topics/class-based-views/index.txt

@@ -24,7 +24,7 @@ Basic examples
 
 Django provides base view classes which will suit a wide range of applications.
 All views inherit from the :class:`~django.views.generic.base.View` class, which
-handles linking the view in to the URLs, HTTP method dispatching and other
+handles linking the view into the URLs, HTTP method dispatching and other
 common features. :class:`~django.views.generic.base.RedirectView` provides a
 HTTP redirect, and :class:`~django.views.generic.base.TemplateView` extends the
 base class to make it also render a template.

docs/topics/performance.txt

@@ -86,7 +86,7 @@ Get things right from the start
 -------------------------------
 
 Some work in optimization involves tackling performance shortcomings, but some
-of the work can be built in to what you'd do anyway, as part of the good
+of the work can be built-in to what you'd do anyway, as part of the good
 practices you should adopt even before you start thinking about improving
 performance.
 

docs/topics/testing/index.txt

@@ -21,7 +21,7 @@ inspect your application's output and generally verify your code is doing what
 it should be doing.
 
 The preferred way to write tests in Django is using the :mod:`unittest` module
-built in to the Python standard library. This is covered in detail in the
+built-in to the Python standard library. This is covered in detail in the
 :doc:`overview` document.
 
 You can also use any *other* Python test framework; Django provides an API and