Drop an extra duplicate word

While doing this, reformat the whole paragraph and also fix the first
one-liner description to match the web site.

This change was r4 in Subversion.

README

@@ -1,12 +1,11 @@
-Lutok is a C++ library to access the Lua C API.
+Lutok is a lightweight C++ API library for Lua.
 
-Lutok provides provides thin C++ wrappers around the Lua C API to ease
-the interaction between C++ and Lua.  These wrappers make intensive use
-of RAII to prevent resource leakage, expose C++-friendly data types,
-report errors by means of exceptions and ensure that the Lua stack is
-always left untouched in the face of errors.  The library also provides
-a small subset of miscellaneous utility functions built on top of the
-wrappers.
+Lutok provides thin C++ wrappers around the Lua C API to ease the
+interaction between C++ and Lua.  These wrappers make intensive use of
+RAII to prevent resource leakage, expose C++-friendly data types, report
+errors by means of exceptions and ensure that the Lua stack is always
+left untouched in the face of errors.  The library also provides a small
+subset of miscellaneous utility functions built on top of the wrappers.
 
 Lutok focuses on providing a clean and safe C++ interface; the drawback
 is that it is not suitable for performance-critical environments.  In