Fix broken Kafka download URL in INSTALL.md (#740)
Fix broken Kafka download URL in INSTALL.md (#740)

Signed-off-by: Alex Chen <3ee76c83eeadc9b0818e0c81000aba3108f91b6c@gmail.com>
matrix-org/dendrite,matrix-org/dendrite,matrix-org/dendrite,matrix-org/dendrite