Clean up E0262 explanation

Author: GuillaumeGomez

src/librustc_error_codes/error_codes/E0262.md

@@ -1,8 +1,12 @@
-Declaring certain lifetime names in parameters is disallowed. For example,
-because the `'static` lifetime is a special built-in lifetime name denoting
-the lifetime of the entire program, this is an error:
+An invalid name was used for a lifetime parameter.
+
+Erroneous code example:
 
 ```compile_fail,E0262
 // error, invalid lifetime parameter name `'static`
 fn foo<'static>(x: &'static str) { }
 ```
+
+Declaring certain lifetime names in parameters is disallowed. For example,
+because the `'static` lifetime is a special built-in lifetime name denoting
+the lifetime of the entire program, this is an error: