s/changesets/differences

Refs #1877

doc/reference.texi

@@ -546,7 +546,7 @@ Most checks are disabled by default.
 @vindex ixfr-from-differences
 
 EXPERIMENTAL: option @code{ixfr-from-differences} is only relevant if you are running Knot DNS as a master for this zone.
-By turning the feature on you tell Knot to create changesets from changes you made to a zone file upon server reload.
+By turning the feature on you tell Knot to create differences from changes you made to a zone file upon server reload.
 See @ref{Controlling running daemon} for more information. Possible values are @code{on} and @code{off}. Disabled by default.
 
 @node disable-any

doc/running.texi

@@ -167,9 +167,9 @@ Or use the @code{-a} again.
 $ knotc -a -c master.conf reload # compile zones and reconfigure
 @end example
 
-If you want @emph{IXFR-out} changesets created from changes you make to a zone file, enable @code{ixfr-from-differences}
+If you want @emph{IXFR-out} differences created from changes you make to a zone file, enable @code{ixfr-from-differences}
 in @code{zones} statement, then compile the zone and reload your server as seen above.
-If @emph{SOA}'s @emph{serial} is not changed no changesets will be created. Please note
+If @emph{SOA}'s @emph{serial} is not changed no differences will be created. Please note
 that this feature is in @emph{experimental} stage and should be used with care.
 If you encounter a bug using this feature, please send it to Knot developers (@pxref{Submitting a bugreport}).