core: Fix capitalization in docs

Author: brson

src/libcore/core.rc

@@ -13,7 +13,7 @@ built-in types and runtime services, or that is used in nearly every
 non-trivial program.
 
 `core` includes modules corresponding to each of the integer types, each of
-THE floating point types, the `bool` type, tuples, characters, strings,
+the floating point types, the `bool` type, tuples, characters, strings,
 vectors (`vec`), shared boxes (`box`), and unsafe pointers (`ptr`).
 Additionally, `core` provides very commonly used built-in types and
 operations, concurrency primitives, platform abstractions, I/O, and complete