Add RESEED_API_KEY to example env vars (#660)

## Status

- Related to onboarding

## What's changed?

- Adds `RESEED_API_KEY`, which is required by our E2E tests but
currently not documented, to `.env.example`.

Author: mwtrew

.env.example

@@ -52,5 +52,8 @@ EDITOR_ENCRYPTION_KEY=a1b2c3d4e5f67890123456789abcdef0123456789abcdef0123456789a
 GOOGLE_CLIENT_ID=changeme.apps.googleusercontent.com
 GOOGLE_CLIENT_SECRET=changeme
 
+# E2E tests can supply this to enable test utility endpoints
+RESEED_API_KEY=changeme
+
 # Enable immediate onboarding for schools
 ENABLE_IMMEDIATE_SCHOOL_ONBOARDING=true

.gitignore

@@ -41,3 +41,6 @@
 .byebug_history
 
 docker-compose.override.yml
+
+# Editor settings
+.idea/*