Add e2ee-default:false docs

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

docs/e2ee.md

@@ -0,0 +1,16 @@
+# End to End encryption by default
+
+By default, Riot will create encrypted DM rooms if the user you are chatting with has keys uploaded on their account.
+For private room creation Riot will default to encryption on but give you the choice to opt-out.
+
+## Disabling encryption by default
+
+Set the following on your homeserver's
+`/.well-known/matrix/client` config:
+```json
+{
+  "im.vector.riot.e2ee": {
+    "default": false
+  }
+}
+```