fix "extention" typo (#1103)

replaces all appearances of "extention" with "extension"

.local/bin/queueandnotify

@@ -2,7 +2,7 @@
 
 # Podboat sucks. This script replaces it.
 # It reads the newsboat queue, queuing downloads with taskspooler.
-# It also removes the junk from extentions.
+# It also removes the junk from extensions.
 queuefile="${XDG_DATA_HOME:-$HOME/.local/share}/newsboat/queue"
 
 while read -r line; do