readme: minor text fix & included the list of test frameworks
readme: minor text fix & included the list of test frameworks

bitrise-io/sample-apps-ios-unit-and-other-tests,bazscsa/sample-apps-ios-unit-and-other-tests,bitrise-io/sample-apps-ios-unit-and-other-tests,iOSTestApps/sample-apps-ios-unit-and-other-tests,bazscsa/sample-apps-ios-unit-and-other-tests,bazscsa/sample-apps-ios-unit-and-other-tests,iOSTestApps/sample-apps-ios-unit-and-other-tests,bazscsa/sample-apps-ios-unit-and-other-tests,bitrise-io/sample-apps-ios-unit-and-other-tests,iOSTestApps/sample-apps-ios-unit-and-other-tests