style(headers): use regular doc-comments inside macros

A bug (rust-lang/rust#23812) in rustc prevented the use of normal
comments inside macros but this has been fixed.

src/header/common/location.rs

@@ -1,34 +1,34 @@
 header! {
-    #[doc="`Location` header, defined in"]
-    #[doc="[RFC7231](http://tools.ietf.org/html/rfc7231#section-7.1.2)"]
-    #[doc=""]
-    #[doc="The `Location` header field is used in some responses to refer to a"]
-    #[doc="specific resource in relation to the response.  The type of"]
-    #[doc="relationship is defined by the combination of request method and"]
-    #[doc="status code semantics."]
-    #[doc=""]
-    #[doc="# ABNF"]
-    #[doc="```plain"]
-    #[doc="Location = URI-reference"]
-    #[doc="```"]
-    #[doc=""]
-    #[doc="# Example values"]
-    #[doc="* `/People.html#tim`"]
-    #[doc="* `http://www.example.net/index.html`"]
-    #[doc=""]
-    #[doc="# Examples"]
-    #[doc="```"]
-    #[doc="use hyper::header::{Headers, Location};"]
-    #[doc=""]
-    #[doc="let mut headers = Headers::new();"]
-    #[doc="headers.set(Location(\"/People.html#tim\".to_owned()));"]
-    #[doc="```"]
-    #[doc="```"]
-    #[doc="use hyper::header::{Headers, Location};"]
-    #[doc=""]
-    #[doc="let mut headers = Headers::new();"]
-    #[doc="headers.set(Location(\"http://www.example.com/index.html\".to_owned()));"]
-    #[doc="```"]
+    /// `Location` header, defined in
+    /// [RFC7231](http://tools.ietf.org/html/rfc7231#section-7.1.2)
+    ///
+    /// The `Location` header field is used in some responses to refer to a
+    /// specific resource in relation to the response.  The type of
+    /// relationship is defined by the combination of request method and
+    /// status code semantics.
+    ///
+    /// # ABNF
+    /// ```plain
+    /// Location = URI-reference
+    /// ```
+    ///
+    /// # Example values
+    /// * `/People.html#tim`
+    /// * `http://www.example.net/index.html`
+    ///
+    /// # Examples
+    /// ```
+    /// use hyper::header::{Headers, Location};
+    ///
+    /// let mut headers = Headers::new();
+    /// headers.set(Location("/People.html#tim".to_owned()));
+    /// ```
+    /// ```
+    /// use hyper::header::{Headers, Location};
+    ///
+    /// let mut headers = Headers::new();
+    /// headers.set(Location("http://www.example.com/index.html".to_owned()));
+    /// ```
     // TODO: Use URL
     (Location, "Location") => [String]