docs: updated chainHub sections

Author: amessbee

main/guides/orchestration/getting-started/key-concepts.md

@@ -32,7 +32,7 @@ See [getBrandInfo](https://agoric-sdk.pages.dev/interfaces/_agoric_orchestration
 const brandInfo = orchestrator.getBrandInfo('denom');
 ```
 
-- `asAmount`converts a denom amount to an `Amount` with a brand. See [asAmount](https://agoric-sdk.pages.dev/interfaces/_agoric_orchestration.Orchestrator#asAmount).
+- `asAmount` converts a denom amount to an `Amount` with a brand. See [asAmount](https://agoric-sdk.pages.dev/interfaces/_agoric_orchestration.Orchestrator#asAmount).
 
 ```javascript
 const amount = orchestrator.asAmount({ denom: 'uatom', value: 1000n });
@@ -81,15 +81,43 @@ await orchestrationAccount.deposit(payment);
 
 ## ChainHub
 
-The `makeChainHub` utility manages the connections and metadata for various blockchain 
-networks. It creates a new `ChainHub` instance implementing the [`ChainHubI`](https://github.com/Agoric/agoric-sdk/blob/000693442f821c1fcea007a2df740733b1f75ebe/packages/orchestration/src/exos/chain-hub.js#L70-L80C4) interface.
-
-It simplifies accessing and interacting with multiple chains, providing a unified interface
- for the orchestration logic to manage cross-chain operations effectively.
-ChainHub also allows dynamic registration and use of chain and connection information.
+ChainHub is a centeralized registry of chains, connections, and denoms 
+that simplifies accessing and interacting with multiple chains, providing
+a unified interface for the orchestration logic to manage cross-chain
+operations effectively. A chainHub instance can be created using a call
+to `makeChainHub` that makes a new ChainHub in the zone (or in the heap
+if no [zone](/glossary/#zone) is provided). The resulting object is an [Exo](/glossary/#exo) singleton.
+It has no precious state. Its only state is a cache of queries to
+`agoricNames` and the info provided in registration calls. When you
+need a newer version you can simply make a hub and repeat the registrations.
+ChainHub allows dynamic registration and use of chain and connection
+information using the following API.
+
+
+### Registration APIs
+
+- `registerChain` register a new chain with `chainHub`. The name will override
+a name in well known chain names. If a durable zone was not provided,
+registration will not survive a reincarnation of the vat, and will have to be
+registered again.
+- `registerConnection` registers a connections between two given chain IDs.
+- `registerAsset` registers an asset that may be held on a chain other than
+the issuing chain. Both corresponding chains should already be registered
+before this call.
+
+### Information Retrieval
+
+-`getChainInfo` takes a chain name to get chain info.
+- `getConnectionInfo` returns `Vow<IBCConnectionInfo>` for two given chain IDs. 
+- `getChainsAndConnection` is used to get chain and connection info give primary and counter chain names.
+- `getAsset` retrieves holding, issuing chain names etc. for a denom.
+- `getDenom` retrieves denom (string) for a `Brand`.
+
+In the below example, `chainHub` is used to register a new chain and establish a connection 
+between the Agoric chain and the newly registered chain.
 
 ```javascript
-const chainHub = makeChainHub(remotePowers.agoricNames);
+const chainHub = makeChainHub(privateArgs.agoricNames, vowTools);
 
 // Register a new chain with its information
 chainHub.registerChain(chainKey, chainInfo);
@@ -102,9 +130,6 @@ chainHub.registerConnection(
 );
 ```
 
-In this example, `chainHub` is used to register a new chain and establish a connection 
-between the Agoric chain and the newly registered chain.
-
 ## Interchain Account (ICA)
 
 [Interchain Accounts](/glossary/#interchain-account-ica) (ICAs) are an IBC feature utilized