Help: Fix typos

 Psuedo -> Pseudo

 behaviour -> behavior

CMake uses American spelling.

Help/manual/cmake-buildsystem.7.rst

@@ -634,7 +634,7 @@ target at a time.  The commands :command:`add_definitions`,
 a similar function, but operate at directory scope instead of target
 scope for convenience.
 
-Psuedo Targets
+Pseudo Targets
 ==============
 
 Some target types do not represent outputs of the buildsystem, but only inputs

Help/manual/cmake-developer.7.rst

@@ -703,7 +703,7 @@ If the package provides Xxx_INCLUDE_DIRS and Xxx_LIBRARIES variables, the
 include dirs and libraries for all components which were requested and which
 have been found should be added to those two variables.
 
-To get this behaviour you can use the FIND_PACKAGE_HANDLE_STANDARD_ARGS()
+To get this behavior you can use the FIND_PACKAGE_HANDLE_STANDARD_ARGS()
 macro, as an example see FindJPEG.cmake.
 
 For internal implementation, it's a generally accepted convention that