Use the LZ4 algorithm to compress metadata when the corresponding feature is enabled

@@ -241,17 +241,18 @@
 \fBlzjb\fR. It is also approximately 80% faster on decompression, while
 giving approximately 10% better compression ratio.
 
 When the \fBlz4_compress\fR feature is set to \fBenabled\fR, the
 administrator can turn on \fBlz4\fR compression on any dataset on the
-pool using the \fBzfs\fR(1M) command. Please note that doing so will
-immediately activate the \fBlz4_compress\fR feature on the underlying
-pool (even before any data is written), and the feature will not be
-deactivated. Since this feature is not read-only compatible, this
-operation will render the pool unimportable on systems without support
-for the \fBlz4_compress\fR feature. Booting off of \fBlz4\fR-compressed
-root pools is supported.
+pool using the \fBzfs\fR(1M) command. Also, all newly written metadata
+will be compressed with \fBlz4\fR algorithm. Since this feature is not
+read-only compatible, this operation will render the pool unimportable
+on systems without support for the \fBlz4_compress\fR feature. Booting
+off of \fBlz4\fR-compressed root pools is supported.
+
+This feature becomes \fBactive\fR as soon as it is enabled and will
+never return to being \fBenabled\fB.
 .RE
 
 .sp
 .ne 2
 .na