Merge pull request #236 from petertseng/sum-of-multiples-wip

sum-of-multiples: Note change in flight in README

sum-of-multiples.md

@@ -4,4 +4,16 @@ multiples of either 3 or 5, we get 3, 5, 6 and 9, 10, 12, 15, and 18.
 The sum of these multiples is 78.
 
 Write a program that can find the sum of the multiples of a given set of
-numbers. If no set of numbers is given, default to 3 and 5.
+numbers.
+
+This exercise is currently under revision.
+You are still free to do this exercise and submit solutions.
+Depending on whether this track has been updated recently,
+the tests may differ between this track and other tracks.
+
+In most tracks, the set of numbers must be explicitly provided.
+In some other tracks, if no set of numbers is given, it defaults to 3 and 5.
+We would like all tracks to require the set of numbers be explicit.
+
+If you would like to help out, please join us at
+https://github.com/exercism/x-common/issues/198.