Update link to disclosure section in charter

The URL was pointing at the previous charter. Also, publication rules require
that the link be to the discoluse section of the group charter:
https://www.w3.org/pubrules/doc/rules/?profile=IG-NOTE#patPolReq

index.html

@@ -26,7 +26,7 @@
         ],
         wg: "Media & Entertainment Interest Group",
         wgURI: "https://www.w3.org/2011/webtv/",
-        charterDisclosureURI: "https://www.w3.org/2017/03/webtv-charter.html",
+        charterDisclosureURI: "https://www.w3.org/2019/06/me-ig-charter.html#patentpolicy",
         github: {
           repoURL: "https://github.com/w3c/me-media-timed-events/",
           branch: "master"