WIP draft of numbers concept (exercism#792)

* WIP draft of numbers concept

* enlarged/corrected section on rounding

* added section on isapprox() for floats

---------

Co-authored-by: Colin Leach <[email protected]>

Author: colinleach

concepts/comments/.meta/config.json renamed to concepts.wip/comments/.meta/config.json

@@ -0,0 +1,7 @@
+{
+  "authors": [
+    "colinleach"
+  ],
+  "contributors": [],
+  "blurb": "Number-crunching is at the heart of Julia, so the language aims to make this fast, flexible and sophisticated."
+}