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/calligrasheets.md

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