calligra*: add pages (#9565)

* Add `calligra` pages:
- `calligrastage`
- `calligrawords`
- `calligrasheets`

* Add examples without arguments

* Add `calligraflow` page

* Add `See also` links

* Simplify grammar for the last examples

pages/common/calligraflow.md

@@ -0,0 +1,17 @@
+# calligraflow
+
+> Calligra's flowchart and diagram application.
+> See also: `calligrastage`, `calligrawords`, `calligrasheets`.
+> More information: <https://manned.org/calligraflow>.
+
+- Launch the flowchart and diagram application:
+
+`calligraflow`
+
+- Open a specific file:
+
+`calligraflow {{path/to/file}}`
+
+- Display help or version:
+
+`calligraflow --{{help|version}}`