Improve documentation

Signed-off-by: Oliver Sand <oliver.sand@sda-se.com>

docs/features/software-templates/writing-templates.md

@@ -271,6 +271,7 @@ template. These follow the same standard format:
 ```yaml
 - id: fetch-base # A unique id for the step
   name: Fetch Base # A title displayed in the frontend
+  if: '{{ parameters.name }}' # Optional condition, skip the step if not truthy
   action: fetch:cookiecutter # an action to call
   input: # input that is passed as arguments to the action handler
     url: ./template

packages/catalog-model/src/schema/kinds/Template.v1beta2.schema.json

@@ -132,7 +132,7 @@
                   },
                   "if": {
                     "type": ["string", "boolean"],
-                    "description": "A templated condition that skips the step when evaluated to false. If the condition is true or not defined, the step is executed."
+                    "description": "A templated condition that skips the step when evaluated to false. If the condition is true or not defined, the step is executed. The condition is true, if the input is not `false`, `undefined`, `null`, `\"\"`, `0`, or `[]`."
                   }
                 }
               }