remove disjointness->disjointedness

While `disjointness` is missing from the OED and other mainstream
dictionaries, it is commonly used to descrbe disjoint sets in the
context of mathematics.

Author: DimitriPapadopoulos

codespell_lib/data/dictionary.txt

@@ -22301,7 +22301,6 @@ disired->desired
 disires->desires
 disiring->desiring
 disitributions->distributions
-disjointness->disjointedness
 diskrete->discrete
 diskretion->discretion
 diskretization->discretization

codespell_lib/data/dictionary_rare.txt

@@ -92,6 +92,7 @@ discontentment->discontent
 discreet->discrete
 discus->discuss
 discuses->discusses
+disjointness->disjointedness
 disturbative->distributive, disruptive,
 doest->does, doesn't,
 empress->impress