Fix note on -P in the 4.4.0 release notes

Reported-by: Lars Henriksen <LarsHenriksen@get2net.dk>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

CHANGES.md

@@ -6,7 +6,9 @@ Version 4.4.0 (2019-02-21)
 
 - Compatibility notes:
 
-    * The -F option was renamed to -P; please use -P instead.
+    * The -F option is superseded by -P which can be used to *remove* certain
+      entries from the data file (instead of keeping them). Please consult the
+      man page for details.
 
 - New features:
 

doc/calcurse.1.txt

@@ -203,7 +203,7 @@ displays those for yesterday and today. The first form is equivalent to *-Q
 *-F*, *--filter*::
   Deprecated, see <<_purge,-P, --purge>>. Note that this option is for
   backward compatibility and not the same as *-P* (it does not use the invert
-  filter option.
+  filter option).
 
 *-g*, *--gc*::
   Run the garbage collector for note files. The garbage collector removes