Addressing style errors

Author: borsakv

src/concurrency.md

@@ -2,7 +2,7 @@ r[concurrency]
 # Concurrency
 
 r[concurrency.intro]
-Rust provides language and library features for writing concurrent programs. These features are designed to prevent [data races] — situations in which multiple threads access the same memory without proper synchronization, with at least one of the accesses modifying that memory.
+Rust provides language and library features for writing concurrent programs. These features are designed to prevent [data races] --- situations in which multiple threads access the same memory without proper synchronization, with at least one of the accesses modifying that memory.
 
 This chapter describes the traits, types, and concepts that Rust uses to express and enforce safe concurrency.
 
@@ -21,7 +21,7 @@ r[concurrency.send-and-sync.send]
 ### Send
 
 r[concurrency.send-and-sync.send.intro]
-The [`Send`] trait indicates that ownership of values of a type can be safely transferred between threads. 
+The [`Send`] trait indicates that ownership of values of a type can be safely transferred between threads.
 
 r[concurrency.send-and-sync.send.rules]
 1. A type that implements [`Send`] can be moved to another thread and used there without causing data races or other [undefined behavior].
@@ -35,8 +35,6 @@ r[concurrency.send-and-sync.send.negative-implementation]
 Types that manage non-thread-safe resources (such as raw pointers or unsynchronized interior mutability) may explicitly opt out of [`Send`] by providing a negative implementation (`!Send`).
 
 ```rust
-#![feature(negative_impls)]
-
 struct SpecialThreadToken(u8);
 
 impl !Send for SpecialThreadToken {}
@@ -60,8 +58,6 @@ r[concurrency.send-and-sync.sync.negative-implementation]
 Types with interior mutability that is not synchronized for concurrent access may explicitly opt out of [`Sync`] by providing a negative implementation (`!Sync`).
 
 ```rust
-#![feature(negative_impls)]
-
 struct SpecialThreadToken(u8);
 
 impl !Sync for SpecialThreadToken {}

src/glossary.md

@@ -147,9 +147,9 @@ affect locality.
 
 ### Marker trait
 A trait that has no associated items (no methods, no associated types, and no constants)
-and is used only to mark that a type has a particular property. 
-Implementing a marker trait does not change a type’s behavior at runtime; 
-it simply communicates to the compiler and to other code that the type satisfies some condition.  
+and is used only to mark that a type has a particular property.
+Implementing a marker trait does not change a type’s behavior at runtime;
+it simply communicates to the compiler and to other code that the type satisfies some condition.
 
 ### Module