Fix casing of function names.

Doc/api/concrete.tex

@@ -3005,9 +3005,9 @@ either the abstract object protocol (including
 or the abstract number protocol (including
 \cfunction{PyNumber_Add()}, \cfunction{PyNumber_Subtract()},
 \cfunction{PyNumber_Or()}, \cfunction{PyNumber_Xor()},
-\cfunction{PyNumber_InplaceAdd()}, \cfunction{PyNumber_InplaceSubtract()},
-\cfunction{PyNumber_InplaceOr()}, and \cfunction{PyNumber_InplaceXor()}).
-Note, \cfunction{PyNumber_InplaceSubtract()} is also useful clearing
+\cfunction{PyNumber_InPlaceAdd()}, \cfunction{PyNumber_InPlaceSubtract()},
+\cfunction{PyNumber_InPlaceOr()}, and \cfunction{PyNumber_InPlaceXor()}).
+Note, \cfunction{PyNumber_InPlaceSubtract()} is also useful clearing
 clearing a set (\code{s-=s}).                         
                       
 \begin{ctypedesc}{PySetObject}