Fix gitignore after Matt messed with it

Author: dalcinl

.gitignore

@@ -11,12 +11,12 @@ __pycache__
 *.pyc
 *.pyo
 .tox
-#petsc4py.PETSc.c
-#petsc4py.PETSc*.h
-#src/libpetsc4py/libpetsc4py.[hc]
-Cython-0.22.1-py2.7-macosx-10.9-intel.egg
-src/petsc4py.PETSc.c
-src/include/petsc4py/petsc4py.PETSc.h
-src/include/petsc4py/petsc4py.PETSc_api.h
-src/libpetsc4py/libpetsc4py.c
-src/libpetsc4py/libpetsc4py.h
+
+## Please don't mess with .gitignore. If you really hate `git status`
+## showing Cython-generated files, please add the following lines
+## (without the comment marks) to `.git/info/exclude`.
+
+# Cython-*.egg
+# petsc4py.PETSc.c
+# petsc4py.PETSc*.h
+# src/libpetsc4py/libpetsc4py.[hc]