Update changelog with --require flag

Change-Id: I4ab29b2a3cd5e8dd4f66bdf1d3f2670e7925b7d3
Reviewed-on: http://gerrit.causes.com/44293
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>

Author: sds

CHANGELOG.md

@@ -36,6 +36,8 @@
 * Fix `PropertySpelling` linter to check the names of nested properties
 * Add `--out` flag which allows the output of the last formatter specified via
   the `--format` flag to be redirected to a file
+* Add `--require` flag allowing arbitrary Ruby modules to be loaded (facilitating
+  custom reporters)
 
 ## 0.29.0