Add Governor to governance README (#1250)

* feat: update README

* feat: add extensions

packages/governance/README.md

@@ -6,10 +6,21 @@ This crate includes primitives for on-chain governance.
 
 ### Interfaces
 
+- [`IGovernor`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#IGovernor)
 - [`ITimelock`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#ITimelock)
 - [`IVotes`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#IVotes)
 
 ### Components
 
+- [`GovernorComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorComponent)
 - [`TimelockControllerComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#TimelockControllerComponent)
 - [`VotesComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#VotesComponent)
+
+#### Governor Extensions
+
+- [`GovernorCoreExecutionComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorCoreExecutionComponent)
+- [`GovernorCountingSimpleComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorCountingSimpleComponent)
+- [`GovernorSettingsComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorSettingsComponent)
+- [`GovernorVotesComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorVotesComponent)
+- [`GovernorVotesQuorumFractionComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorVotesQuorumFractionComponent)
+- [`GovernorTimelockExecutionComponent`](https://docs.openzeppelin.com/contracts-cairo/0.20.0-rc.0/api/governance#GovernorTimelockExecutionComponent)