Blurb on dirty runs

ENVIRONMENT.md

@@ -2,6 +2,7 @@
 
 ## Complement-Crypto Configuration
 Complement-Crypto is configured exclusively through the use of environment variables. These variables are described below. Additional environment variables can be used, and are outlined at https://github.com/matrix-org/complement/blob/main/ENVIRONMENT.md 
+Complement-Crypto always runs in dirty mode (homeservers exist for the entire duration of the test suite) for performance reasons.
 
 #### `COMPLEMENT_CRYPTO_TCPDUMP`
 If 1, automatically attempts to run `tcpdump` when the containers are running. Stops dumping when tests complete. This will probably require you to run `go test` with `sudo -E`. The `.pcap` file is written to `tests/test.pcap`.  

cmd/gendoc/main.go

@@ -128,6 +128,7 @@ func main() {
 		"",
 		"## Complement-Crypto Configuration",
 		"Complement-Crypto is configured exclusively through the use of environment variables. These variables are described below. Additional environment variables can be used, and are outlined at https://github.com/matrix-org/complement/blob/main/ENVIRONMENT.md ",
+		"Complement-Crypto always runs in dirty mode (homeservers exist for the entire duration of the test suite) for performance reasons.",
 	}
 	for _, vd := range varDocs {
 		mdFileLines = append(mdFileLines, fmt.Sprintf("\n#### `%v`", vd.Name))