fix($theme-default): bitbucket edit link goes to wrong link (close: #1235) (#1248)

Author: nickngqs

packages/@vuepress/theme-default/components/Page.vue

@@ -145,6 +145,7 @@ export default {
           : repo
         return (
           base.replace(endingSlashRE, '') +
+           `/src` +
            `/${docsBranch}` +
            (docsDir ? '/' + docsDir.replace(endingSlashRE, '') : '') +
            path +