Improve footnote wording

Signed-off-by: Graham <gpe@openrs2.org>

archive/src/main/resources/org/openrs2/archive/templates/caches/index.html

@@ -68,7 +68,7 @@
 				are empty. As XTEA does not hide the length of the compressed
 				data, this service infers which encrypted loc groups are empty
 				and includes them in the number of valid keys, regardless of
-				whether we know the key or not. After downloading a cache from
+				whether the key is known or not. After downloading a cache from
 				this service, a cache editor may be used to replace the empty
 				encrypted loc groups with unencrypted replacements.
 			</p>