Update CHANGES (releng for 2.1).
Update CHANGES (releng for 2.1).

Change-Id: I4f318d6c4487836b71476754014094873f20413f
Signed-off-by: Piotr Sikora <321b1a11e6b8c7ca12f1b0b438664e52a48b555e@frickle.com>

lilien1010/ngx_cache_purge,FRiCKLE/ngx_cache_purge,FRiCKLE/ngx_cache_purge,ainoya/ngx_cache_purge,lilien1010/ngx_cache_purge,ainoya/ngx_cache_purge