rst bge touch ups: making the title of the examples slightly more noticeable

-  it's still not correct, comparing to the other examples, but at least it looks okish.
-  fixed some small typos

doc/python_api/examples/bge.constraints.py

@@ -1,6 +1,6 @@
 """
 Basic Physics Constraint
-++++++++++++++++++++++
+++++++++++++++++++++++++
 Example of how to create a hinge Physics Constraint between two objects.
 """
 from bge import logic

doc/python_api/examples/bge.texture.1.py

@@ -1,6 +1,6 @@
 """
-Texture replacement
-++++++++++++++++++++++
+Texture Replacement
++++++++++++++++++++
 Example of how to replace a texture in game with an external image.
 createTexture() and removeTexture() are to be called from a module Python
 Controller.

doc/python_api/examples/bge.texture.py

@@ -1,6 +1,6 @@
 """
 Basic Video Playback
-++++++++++++++++++++++
+++++++++++++++++++++
 Example of how to replace a texture in game with a video. It needs to run everyframe
 """
 import bge