qalc: add page (#13297)

* qalc: add page

* Fix example description

* Update pages/common/qalc.md

Co-authored-by: spageektti <git@spageektti.cc>

---------

Co-authored-by: spageektti <git@spageektti.cc>

pages/common/qalc.md

@@ -0,0 +1,29 @@
+# qalc
+
+> Powerful and easy to use command-line calculator.
+> See also: `bc`.
+> More information: <https://qalculate.github.io/manual/qalc.html>.
+
+- Launch in [i]nteractive mode:
+
+`qalc {{--interactive}}`
+
+- Launch in [t]erse mode (print the results only):
+
+`qalc --terse`
+
+- Update currency [e]xchange rates:
+
+`qalc --exrates`
+
+- Perform calculations non-interactively:
+
+`qalc {{66+99|2^4|6 feet to cm|1 bitcoin to USD|20 kmph to mph|...}}`
+
+- List all supported functions/prefixes/units/variables:
+
+`qalc --{{list-functions|list-prefixes|list-units|list-variables}}`
+
+- Execute commands from a [f]ile:
+
+`qalc --file {{path/to/file}}`