chore: update links to WebAssembly/threads issues (#301)

Author: rawkode

meetings/2020/WASI-07-16.md

@@ -31,9 +31,9 @@ Installation is required, see the calendar invite.
         1. What kinds of tests should be in an official testsuite?
         1. Where should we collect them?
     1. Discussion topic: Threads
-        1. WebAssembly/threads#8
-        1. WebAssembly/threads#95
-        1. WebAssembly/threads#138
+        1. https://github.com/WebAssembly/threads/issues/8
+        1. https://github.com/WebAssembly/threads/issues/95
+        1. https://github.com/WebAssembly/threads/issues/138
     1. Discussion topic: `fd_seek` past the end of a file on Windows
         1. https://github.com/WebAssembly/WASI/issues/292
     1. Discussion topic: Symbolic links and Windows