Update REACTION_INVALID error message

Author: delivrance

compiler/errors/source/400_BAD_REQUEST.tsv

@@ -249,7 +249,7 @@ RANDOM_ID_INVALID	The provided random ID is invalid
 RANDOM_LENGTH_INVALIDThe random length is invalid
 RANGES_INVALIDInvalid range provided
 REACTION_EMPTYThe reaction provided is empty
-REACTION_INVALIDInvalid reaction provided (only emoji are allowed)
+REACTION_INVALIDInvalid reaction provided (only valid emoji are allowed)
 REFLECTOR_NOT_AVAILABLEThe call reflector is not available
 REPLY_MARKUP_BUY_EMPTYReply markup for buy button empty
 REPLY_MARKUP_GAME_EMPTYThe provided reply markup for the game is empty