Add description for two exceptions which handled by DefaultHandlerExceptionResolver in reference document
Add description for two exceptions which handled by DefaultHandlerExceptionResolver in reference document

* MissingPathVariableException (Available since 4.2)
* NoHandlerFoundException (Available since 4.0)

spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework,spring-projects/spring-framework