Correct description of directive example (#506)

* Correct description of directive example

fixes #505

* Fix 80c wrapping

Author: anmonteiro

spec/Section 3 -- Type System.md

@@ -1649,8 +1649,7 @@ provide the `@deprecated` directive if representing deprecated portions of
 the schema.
 
 Directives must only be used in the locations they are declared to belong in.
-In this example, a directive is defined which can be used to annotate a
-fragment definition:
+In this example, a directive is defined which can be used to annotate a field:
 
 ```graphql example
 directive @example on FIELD