[client] Mark the Bloom filter predicate method as experimental

This is the method meant for general consumption by C++ client
users. The method that directly accepts BlockBloomFilter
is already marked Advanced/Unstable.

This allows changes in future in case we need to incorporate
feedback discovered when testing integration with Impala

Tests:
- Verified the generated doxygen HTML file.

Change-Id: Ie1572228dc041d2e5cba68ee47afbb082752b759
Reviewed-on: http://gerrit.cloudera.org:8080/15486
Reviewed-by: Adar Dembo <[email protected]>
Tested-by: Kudu Jenkins

src/kudu/client/client.h

@@ -1089,6 +1089,8 @@ class KUDU_EXPORT KuduTable : public sp::enable_shared_from_this<KuduTable> {
   /// Create a new IN Bloom filter predicate which can be used for scanners on
   /// this table.
   ///
+  /// @note This method is experimental and may change or disappear in future.
+  ///
   /// A Bloom filter is a space-efficient probabilistic data structure used to
   /// test set membership with a possibility of false positive matches.
   /// See @c KuduBloomFilter for creating Bloom filters.