chore(readme): Correct CDK Construction Zone S1E5 Twitch Link (aws#15646

)

This change corrects the episode link, both within a browser and with
the youtube-dl tool it shows as a non-existent video with the current
link.

youtube-dl output
```bash
youtube-dl https://www.twitch.tv/aws/video/977551207
[twitch:vod] 977551207: Downloading stream metadata GraphQL
ERROR: Video 977551207 does not exist
```


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

README.md

@@ -160,7 +160,7 @@ this capability, please see the
     * [S1E2](https://www.twitch.tv/videos/925801382): Triggers (part 2); **Participants:** @NetaNir, @eladb, @iliapolo 
     * [S1E3](https://www.twitch.tv/videos/944565768): Triggers (part 3); **Participants:** @NetaNir, @eladb, @iliapolo, @RomainMuller
   * [S1E4](https://www.twitch.tv/aws/video/960287598): [Tokens](https://docs.aws.amazon.com/cdk/latest/guide/tokens.html) Deep Dive; **Participants:** @NetaNir,@rix0rrr, @iliapolo, @RomainMuller
-  * [S1E5](https://www.twitch.tv/aws/video/977551207): [Assets](https://docs.aws.amazon.com/cdk/latest/guide/assets.html) Deep Dive; **Participants:** @NetaNir, @eladb, @jogold
+  * [S1E5](https://www.twitch.tv/videos/981481112): [Assets](https://docs.aws.amazon.com/cdk/latest/guide/assets.html) Deep Dive; **Participants:** @NetaNir, @eladb, @jogold
   * [S1E6](https://www.twitch.tv/aws/video/1005334364): [Best Practices](https://aws.amazon.com/blogs/devops/best-practices-for-developing-cloud-applications-with-aws-cdk/); **Participants:** @skinny85, @eladb, @rix0rrr, @alexpulver
   * [S1E7](https://www.twitch.tv/videos/1019059654): Tips and Tricks From The CDK Team; **Participants:** All the CDK team! 
 * [Examples](https://github.com/aws-samples/aws-cdk-examples)