man1/flux-kvs: Add clarification on get --watch

Note that the --watch option watches for all times a key is written
to, not if it changes.

doc/man1/flux-kvs.adoc

@@ -76,7 +76,7 @@ added. If '-j', value is interpreted as encoded JSON and formatted accordingly.
 If '-r', value is displayed without a newline.  If '-t', the RFC 11 object
 is displayed.  '-a treeobj' causes the lookup to be relative to an RFC 11
 snapshot reference.  If '-w', after the initial value, display the
-new value each time the key changes until interrupted, or if '-c count'
+new value each time the key is written to until interrupted, or if '-c count'
 is specified, until 'count' values have been displayed.  If the
 initial value does not yet exist, `-W` can be specified to wait for it
 to be created.