Move file name extensions from "expect.txt" to "excludes.txt"

.github/actions/spell-check/excludes.txt

@@ -25,7 +25,12 @@ ignore$
 \.jpg$
 \.lcl$
 \.lock$
+\.mdtext$
+\.mdtxt$
+\.mdwn$
 \.min\.
+\.mkd$
+\.mkdn$
 \.mod$
 \.pdf$
 \.PNG$

.github/actions/spell-check/expect.txt

@@ -1185,9 +1185,6 @@ MAXIMIZEBOX
 MAXSHORTCUTSIZE
 maxversiontested
 MBs
-mdtext
-mdtxt
-mdwn
 MBUTTON
 MBUTTONDBLCLK
 MBUTTONDOWN
@@ -1232,9 +1229,7 @@ minlevel
 Miracast
 mirophone
 mjpg
-mkd
 mkdir
-mkdn
 mlcfg
 mmdeviceapi
 mmi