Deprecate the nu_scripts version of stdlib-candidate (#1042)

Deprecates the existing `stdlib-candidate` directories in `nu_scripts`
since `std-rfc` has now transitioned to the main repo. Updates readme
and renamed directories.

stdlib-candidate-archive/std-rfc/tables/reject-column-ranges.nu

@@ -0,0 +1,13 @@
+use ./col-indices.nu *
+
+# Reject a range of columns by their indices
+#
+# Example:
+#
+# ls | reject column-ranges 0 4 5 | first 3
+export def "reject column-ranges" [
+    ...ranges
+] {
+    let column_selector = ($in | col-indices ...$ranges)
+    $in | reject ...$column_selector
+}