Updated test case documentation

docs/test_cases/t20005.md

@@ -0,0 +1,45 @@
+# t20005 - Class template basic sequence diagram
+## Config
+```yaml
+compilation_database_dir: ..
+output_directory: puml
+diagrams:
+  t20005_sequence:
+    type: sequence
+    glob:
+      - ../../tests/t20005/t20005.cc
+    include:
+      namespaces:
+        - clanguml::t20005
+    using_namespace:
+      - clanguml::t20005
+    start_from:
+      - function: "clanguml::t20005::C<T>::c"
+```
+## Source code
+File t20005.cc
+```cpp
+namespace clanguml {
+namespace t20005 {
+
+template <typename T> struct A {
+    T a(T arg) { return arg; }
+};
+
+template <typename T> struct B {
+    T b(T arg) { return a_.a(arg); }
+
+    A<T> a_;
+};
+
+template <typename T> struct C {
+    T c(T arg) { return b_.b(arg); }
+
+    B<T> b_;
+};
+
+}
+}
+```
+## Generated UML diagrams
+![t20005_sequence](./t20005_sequence.svg "Class template basic sequence diagram")