Added start and end of keyword testsuite (#1434)

plugins/org.yakindu.sct.doc.user/src/user-guide/sctunit.textile

@@ -844,6 +844,7 @@ p=. Return statement grammar
 
 h3(#sctunit_test_suites). Test suites
 
+==<!-- Start sctunit_keyword_testsuite -->==
 A _test suite_ aggregates a set of "test classes":#sctunit_test_classes into a logical unit. It is contained in a file with a _.sctunit_ filename extension.
 
 ==<div class="example">==
@@ -878,7 +879,7 @@ p=. Test suite grammar
 
 Test suites are namespace-aware: Using the "_package_ statement":#sctunit_the_package_statement, you can insert a test suite into a specific "namespace":#sctunit_namespaces. You can "import":#sctunit_the_import_statement test suites and test classes from the same or from different namespaces into a test suite.
 
-
+==<!-- End sctunit_keyword_testsuite -->==
 
 h3(#sctunit_namespaces). Namespaces