Add feature flag documentation

doc/README.md

@@ -16,6 +16,7 @@
 - [Continuous Integration](continuous-integration.md)
 - [DfE Sign-In](dfe-sign-in.md)
 - [Educational Establishment Personas](school-personas.md)
+- [Feature Flags](feature-flags.md)
 - [Get Information About Schools](gias.md)
 - [Logging](logging.md)
 - [Managing environment variables](managing-environment-variables.md)

doc/feature-flags.md

@@ -0,0 +1,23 @@
+# Feature Flags
+
+Feature flags were introduced to enable functionality to be enabled / disabled within the live environment.
+
+These allowed for:
+- Functionality to be tested  / enabled for a set period of time in live to assess impact
+- Large pieces of functionality to be developed without ‘blocking’ the release pipeline and to discourage a developer from having large chunks of code that is not merged into the main code base
+- Multiple developers to work together on a large piece of new functionality 
+
+On the whole, the use of feature flags is transitional and they should be removed once the need for them has gone.
+
+## Current Flags
+|Flag name|Description|Status|Actions|
+|--|--|--|--|
+|rfh_usability_survey|When enabled, embeds the RfH usability survey in the RfH submission confirmation page.|ENABLED|Feature now live, flag to be removed|
+|customer_satisfaction_survey|When enabled, replaces the existing exit survey with the new customer satisfaction survey.|ENABLED|Feature now live, flag to be removed|
+|maintenance_mode|Special flag, when enabled will prevent user access to the application. Intended for infrastructure or data maintenance.|DISABLED|To be enabled when required|
+|sc_tasklist_tab|When enabled, the task list tab for a case at level 4 or 5 is visible.|ENABLED in development, DISABLED in production|To be enabled when all components of the task list are ready|
+
+## Enabling Disabling feature flags
+Visit https://`<your-environment>`/flipper e.g. https://www.get-help-buying-for-schools.service.gov.uk/flipper and enter the username and password for feature flag access.
+
+The username and password for each environment can be found in Azure within each container app (e.g., `devghbs-buyforyourschool`) in the secrets section of settings on the left hand side.