Fix some links and small wordings

Author: carols10cents

src/ch19-01-unsafe-rust.md

@@ -442,7 +442,7 @@ The final action that works only with `unsafe` is accessing fields of a
 used in a particular instance at one time. Unions are primarily used to
 interface with unions in C code. Accessing union fields is unsafe because Rust
 can’t guarantee the type of the data currently being stored in the union
-instance. You can learn more about unions in [the reference][reference].
+instance. You can learn more about unions in [the Rust Reference][reference].
 
 ### When to Use Unsafe Code
 

src/ch19-06-macros.md

@@ -182,7 +182,7 @@ pub fn some_name(input: TokenStream) -> TokenStream {
 }
 ```
 
-<span class="caption">Listing 19-29: An example of using a procedural
+<span class="caption">Listing 19-29: An example of defining a procedural
 macro</span>
 
 The function that defines a procedural macro takes a `TokenStream` as an input
@@ -484,11 +484,11 @@ Function-like macros define macros that look like function calls. Similarly to
 `macro_rules!` macros, they’re more flexible than functions; for example, they
 can take an unknown number of arguments. However, `macro_rules!` macros can be
 defined only using the match-like syntax we discussed in the section
-[“Declarative Macros with `macro_rules!` for General Metaprogramming”][decl]
-earlier. Function-like macros take a `TokenStream` parameter and their
-definition manipulates that `TokenStream` using Rust code as the other two
-types of procedural macros do. An example of a function-like macro is an `sql!`
-macro that might be called like so:
+[“Declarative Macros with `macro_rules!` for General
+Metaprogramming”][decl]<!-- ignore --> earlier. Function-like macros take a
+`TokenStream` parameter and their definition manipulates that `TokenStream`
+using Rust code as the other two types of procedural macros do. An example of a
+function-like macro is an `sql!` macro that might be called like so:
 
 [decl]: #declarative-macros-with-macro_rules-for-general-metaprogramming