Fix awk parser to set correct variable. (#419)

The awk json parsing routine was setting a variable of "description"
instead of "info". This was causing a problem where the cached index -
and subsequently ls-remote commands - to show the "%info" format item as
the URL again.

fisher.fish

@@ -1171,7 +1171,7 @@ function __fisher_remote_index_update
             }
 
             if (match($0, /^description:[[:blank:]]*/)) {
-                description = substr($0, RLENGTH+1)
+                info = substr($0, RLENGTH+1)
             }
 
             if (match($0, /^stargazers_count:[[:blank:]]*/)) {