Added leak and exec, moved from a config.json file to a .env file, other changes

.env.example

@@ -0,0 +1,18 @@
+# Put MongoDB database URL here
+MONGO=
+
+# Put Discord token here
+TOKEN=
+# Put Cat API token here
+CAT=
+# Put Mashape/RapidAPI key here
+MASHAPE=
+# Put Google API key here
+GOOGLE=
+# Put Google Custom Search ID here
+CSE=
+# Put DBL/top.gg token here
+DBL=
+
+# Put snowflake ID of bot owner here
+OWNER=