docs: add duration docs

Author: kristian-mkd

packages/client/docusaurus/docs/javascript/02-guides/03-call-and-participant-state.mdx

@@ -55,6 +55,7 @@ Here is an excerpt of the call state properties:
 | `createdBy$`             | `createdBy`             | The user who created the call.                                                                               |
 | `custom$`                | `custom`                | Custom data attached to the call.                                                                            |
 | `dominantSpeaker$`       | `dominantSpeaker`       | The participant that is the current dominant speaker of the call.                                            |
+| `duration$`              | `duration`              | The duration since the start of the call in seconds.                                                         |
 | `egress$`                | `egress`                | The egress data of the call (for broadcasting and livestreaming).                                            |
 | `endedAt$`               | `endedAt`               | The time the call was ended.                                                                                 |
 | `endedBy$`               | `endedBy`               | The user who ended the call.                                                                                 |

packages/react-native-sdk/docusaurus/docs/reactnative/03-core/03-call-and-participant-state.mdx

@@ -69,6 +69,7 @@ Here is an excerpt of the available call state hooks:
 | `useCallCreatedAt`                   | The time the call was created.                                                                                |
 | `useCallCreatedBy`                   | The user that created the call.                                                                               |
 | `useCallCustomData`                  | The custom data attached to the call.                                                                         |
+| `useCallDuration`                    | The call duration since the start of the call in seconds.                                                     |
 | `useCallEgress`                      | The egress information of the call.                                                                           |
 | `useCallEndedBy`                     | The user that ended the call.                                                                                 |
 | `useCallIngress`                     | The ingress information of the call.                                                                          |
@@ -205,7 +206,7 @@ const hosts = participants.filter((p) => p.roles.includes('host'));
 
 // participants that publish video and audio
 const videoParticipants = participants.filter(
-  (p) => hasVideo(p) && hasAudio(p),
+  (p) => hasVideo(p) && hasAudio(p)
 );
 ```