Fix some docs summary nits

Author: malbarbo

src/liballoc/fmt.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Utilities for formatting and printing `String`s
+//! Utilities for formatting and printing `String`s.
 //!
 //! This module contains the runtime support for the [`format!`] syntax extension.
 //! This macro is implemented in the compiler to emit calls to this module in

src/libcore/macros.rs

@@ -361,7 +361,7 @@ macro_rules! try {
     })
 }
 
-/// Write formatted data into a buffer
+/// Write formatted data into a buffer.
 ///
 /// This macro accepts a format string, a list of arguments, and a 'writer'. Arguments will be
 /// formatted according to the specified format string and the result will be passed to the writer.

src/libstd/f32.rs

@@ -9,8 +9,9 @@
 // except according to those terms.
 
 //! This module provides constants which are specific to the implementation
-//! of the `f32` floating point data type. Mathematically significant
-//! numbers are provided in the `consts` sub-module.
+//! of the `f32` floating point data type.
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 //!
 //! *[See also the `f32` primitive type](../primitive.f32.html).*
 

src/libstd/f64.rs

@@ -9,8 +9,9 @@
 // except according to those terms.
 
 //! This module provides constants which are specific to the implementation
-//! of the `f64` floating point data type. Mathematically significant
-//! numbers are provided in the `consts` sub-module.
+//! of the `f64` floating point data type.
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
 //!
 //! *[See also the `f64` primitive type](../primitive.f64.html).*
 

src/libstd/panic.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Panic support in the standard library
+//! Panic support in the standard library.
 
 #![stable(feature = "std_panic", since = "1.9.0")]