Fix spelling error(s) (jtv#445)

* Fix spelling error

* Fix another spelling error

BUILDING-cmake.md

@@ -16,7 +16,7 @@ simple words, what needs changing and why.
 Quick start
 -----------
 
-If you just wawnt to get it built and installed quickly, run `cmake` from the
+If you just want to get it built and installed quickly, run `cmake` from the
 root of the libpqxx source tree.  This configures your build.
 
 Then compile libpqxx by running:
@@ -231,7 +231,7 @@ both more secure and more convenient than passwords.
 Install
 -------
 
-Once you've built libpqxx, CMake can also help yuou install the library and
+Once you've built libpqxx, CMake can also help you install the library and
 headers on your system.  The default installation location will vary from one
 operating system to another, but you can set it explicitly.