roachtest: readme notes for finding crdb logs on local deployments

Epic: None
Release note: None

Author: williamchoe3

pkg/cmd/roachtest/README.md

@@ -225,3 +225,19 @@ laptop online. The CI job is run as follows:
   * Changes → Build branch: `<branch>`
   * Parameters → `env.TESTS`: `^<test>$`
   * Parameters → `env.COUNT`: `<runs>`
+
+### Cockroach node logs and artifacts for roachtests running locally
+
+When running tests locally, you may want to inspect cockroach node logs
+`logs/<n>.cockroach.log` or specific channel / stderr logs that are in `<n>.unredacted/`
+e.g.
+* `logs/1.cockroach.log`
+* `logs/1.unredacted/cockroach-kv-distribution.log`
+
+When using roachtest locally, these logs are placed in your home directory in 
+`~/local/<n>/` e.g. `~/local/1/`.
+
+Note: These directories will be cleared when your deployment is being deleted,
+i.e. after your test run. To keep these logs & artifacts use `roachtest run`
+flags `--debug` or `--debug-always` to keep your deployment. See `roachtest run -h`
+for more information.