HBASE-29701 Update README.txt in hbase-protocol-shaded (#7444)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
Signed-off-by: Nihal Jain <nihaljain@apache.org>
(cherry picked from commit 144cd01)

Author: stoty

hbase-protocol-shaded/README.txt

@@ -1,6 +1,9 @@
 This module has proto files used by core. These protos
 overlap with protos that are used by coprocessor endpoints
-(CPEP) in the module hbase-protocol. So core versions have
-a different name, the generated classes are relocated
--- i.e. shaded -- to a new location; they are moved from
-org.apache.hadoop.hbase.* to org.apache.hadoop.hbase.shaded.
+(CPEP) in the module hbase-protocol. To make sure that the
+core versions have a different names, these classes are
+using a different package;
+they are in
+org.apache.hadoop.hbase.shaded.protobuf.generated.*
+, while the hbase-protocol classes are in
+org.apache.hadoop.hbase.protobuf.generated.*.