DevX: Add another Matrix site to docker-compose (#3511)

* remove redis, since we dont use it

* update localhost TLS certificat to add *.othersite.m.localhost wildcard

* allow for federation

* Add services and config files for Matrix site othersite.m.localhost

* add element web instance app.othersite.m.localhost

* update README

* exclude synapse database for othersite.m.localhost

* linting

backend/dev_tls_setup

@@ -34,5 +34,6 @@ subjectAltName = @alt_names
 DNS.1 = localhost
 DNS.2 = m.localhost
 DNS.3 = *.m.localhost
+DNS.4 = *.othersite.m.localhost
 EOF
 )