Added link in glossary to expression-oriented language

Tidied up glossary.md and added link from hello-world.md to
'expression-oriented language' in glossary.md

Author: Dangthrimble

src/doc/trpl/glossary.md

@@ -48,16 +48,16 @@ expression might perform actions other than simply returning a value.
 
 ### Expression-Oriented Language
 
-In early programming languages [expressions] and [statements] were two separate
-syntactic categories: expressions had a value and statements did things.
-However, later languages blurred this distinction, allowing expressions to do
-things and statements to have a value. In an expression-oriented language,
-(nearly) every statement is an expression and therefore returns a value.
-Consequently these expression statements can themselves form part of larger
-expressions.
-
-[expressions]: glossary.html#expression
-[statements]: glossary.html#statement
+In early programming languages [expressions][expression] and
+[statements][statement] were two separate syntactic categories: expressions had
+a value and statements did things. However, later languages blurred this
+distinction, allowing expressions to do things and statements to have a value.
+In an expression-oriented language, (nearly) every statement is an expression
+and therefore returns a value. Consequently these expression statements can
+themselves form part of larger expressions.
+
+[expression]: glossary.html#expression
+[statement]: glossary.html#statement
 
 ### Statement
 

src/doc/trpl/hello-world.md

@@ -111,10 +111,13 @@ string to the screen. Easy enough!
 
 [allocation]: the-stack-and-the-heap.html
 
-Finally, the line ends with a semicolon (`;`). Rust is an ‘expression oriented’
-language, which means that most things are expressions, rather than statements.
-The `;` is used to indicate that this expression is over, and the next one is
-ready to begin. Most lines of Rust code end with a `;`.
+Finally, the line ends with a semicolon (`;`). Rust is an [‘expression oriented’
+language][expression-oriented language], which means that most things are
+expressions, rather than statements. The `;` is used to indicate that this
+expression is over, and the next one is ready to begin. Most lines of Rust code
+end with a `;`.
+
+[expression-oriented language]: glossary.html#expression-oriented-language
 
 Finally, actually compiling and running our program. We can compile with our
 compiler, `rustc`, by passing it the name of our source file: