mate-calc-cmd: add page (#8014)

pages/linux/mate-calc-cmd.md

@@ -0,0 +1,12 @@
+# mate-calc-cmd
+
+> Calculate mathematic expressions in MATE desktop environment in terminal.
+> More information: <https://manned.org/mate-calc-cmd>.
+
+- Start an interactive calculator session:
+
+`mate-calc-cmd`
+
+- Calculate a specific mathematic expession:
+
+`{{2 + 5}}`