Fix typos in Cerebras doc

[henrytwo]

Fix typo in Cerebras documentation

Why are these changes needed?

Fixes typos in the Cerebras integration documentation.

cc: @jackgerrits @afourney @ekzhu @gagb

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[henrytwo]

Also it seems like the title for this page is missing for some reason. Is there any manual editing done prior to the page being published?

https://microsoft.github.io/autogen/docs/topics/non-openai-models/cloud-cerebras

I can see the title on the ipynb file.