Fix comment about sample buckets

This fixes a comment which said that the bucket for the sample may or
may not already exist. That comment was for an earlier iteration of the
code and wasn't updated when the code was changed to require a
pre-existing bucket.

Change-Id: I89ae5367144dfccb183f1234c2dd7ba26a7ee942
Reviewed-on: https://review.couchbase.org/c/ns_server/+/184817
Well-Formed: Build Bot <build@couchbase.com>
Tested-by: Steve Watanabe <steve.watanabe@couchbase.com>
Reviewed-by: Navdeep S Boparai <navdeep.boparai@couchbase.com>

src/menelaus_web_samples.erl

@@ -65,7 +65,7 @@ build_samples_input_list(Samples) ->
 %% The second input is a list of json objects each of which consists of list
 %% of [{"sample", <sample-name>}, {"bucket", <bucket-name>}] where
 %% <sample-name>.zip contains the data and <bucket-name> is the destination
-%% bucket (which may or may not already exist).
+%% bucket (which must already exist).
 %%
 %% Thee two types of input are normalized into a list of tuples to facilitate
 %% common handling of the two.