minor doco tweaks

src/spec/doc/core-testing-guide.adoc

@@ -315,14 +315,11 @@ lower chance to hold critical bugs than a program with no or low coverage. To ge
 the generated byte-code usually needs to be instrumented before the tests are executed. One tool with Groovy support
  for this task is http://cobertura.github.io/cobertura/[Cobertura].
 
-Various frameworks and build tools come with Cobertura integration. For Grails, there is the http://grails.org/plugin/code-coverage[code coverage plugin] based
-on Cobertura, for Gradle there is the https://github.com/eriwen/gradle-cobertura-plugin[gradle-cobertura plugin], to name only two of them.
-
 The following code listing shows an example on how to enable Cobertura test coverage reports in a Gradle build script from
 a Groovy project:
 
 [source,groovy]
----------------------------------------------------------------------
+----
 def pluginVersion = '<plugin version>'
 def groovyVersion = '<groovy version>'
 def junitVersion = '<junit version>'
@@ -353,7 +350,7 @@ cobertura {
     includes = ['**/*.java', '**/*.groovy']
     excludes = ['com/thirdparty/**/*.*']
 }
----------------------------------------------------------------------
+----
 
 Several output formats can be chosen for Cobertura coverage reports and test code coverage reports can be added to
 continuous integration build tasks.