Minor changes in README.md and templates/manifest.gjson

- Change credits to translators in README.md so it mentions all the
  translators and not only Alexander.
- Add bugs/beta version sections to README.md.
- Add author and homepage_url fields to manifest.gjson.

Change-Id: I4580ac64e43de5263586627e5d762d696a9c93b5
diff --git a/templates/manifest.gjson b/templates/manifest.gjson
index 84ba035..f046a8f 100644
--- a/templates/manifest.gjson
+++ b/templates/manifest.gjson
@@ -2,6 +2,8 @@
   "manifest_version": 2,
   "name": "__MSG_appName__",
   "description": "__MSG_appDescription__",
+  "author": "Adrià Vilanova Martínez (@avm99963)",
+  "homepage_url": "https://gerrit.avm99963.com/plugins/gitiles/translateselectedtext/",
   "version": "0",
   "version_name": "dirty",
   "permissions": [