doc: small fixes for python documentation

(cherry picked from commit b1d5c31836a85ac34198bc7a913f2c5341efa6e1)

doc/doxygen/refman.tex

@@ -138,7 +138,7 @@ Documentation License”.
 
 \part{StarPU Extensions}
 
-\chapter{PythonInterface}
+\chapter{Python Interface}
 \label{PythonInterface}
 \hypertarget{PythonInterface}{}
 \input{PythonInterface}