docker (compose): test environment variable + network alias: `SAT_TEST_ENV_E2E` is set to `1` to indicate that e2e environment requirement are available (notably specific accounts and hosts created). The e2e tests needing it won't be launched if this variable is not set. A network alias is set for the backend at `sat.test` (to have a tld available, needed for some network libraries like OpenSSL).

You'll find install instructions in documentation (see doc/installation.rst).

If you need help, come the SàT official XMPP room: sat@chat.jabberfr.org or join us with a web browser via https://chat.jabberfr.org/converse.js/sat@chat.jabberfr.org