Fix the component name regular expression

Currently the expression given matches everything

Author: MikeRalphson

versions/3.0.md

@@ -411,7 +411,7 @@ Field Name | Type | Description
 
 This object can be extended with [Specification Extensions](#specificationExtensions). 
 
-All the fixed fields declared above are objects that MUST use keys that match the regular expression: `[a-zA-Z0-9.\-_]+`.
+All the fixed fields declared above are objects that MUST use keys that match the regular expression: `^[a-zA-Z0-9\.\-_]+$`.
 
 Field Name Examples: