core: More doc tweaks

Author: brson

src/libcore/core.rc

@@ -10,12 +10,12 @@
 #[doc(
     brief = "The Rust core library",
     desc = "
-The core library provides functionality that is closely tied to
-the Rust built-in types and runtime services, or that is used in nearly
-every non-trivial program.
+The core library provides functionality that is closely tied to the Rust
+built-in types and runtime services, or that is used in nearly every
+non-trivial program.
 
-The core library is linked by default to all crates and the contents
-imported. The effect is as though the user had written the following:
+It is linked by default to all crates and the contents imported. The effect is
+as though the user had written the following:
 
 ~~~
 use core;