Directory name mismatch in README instructions

[schwentker]

The git clone command in the README creates a directory named box-ai-api-masterclass, but the cd command references box-ai-api-master-class (with hyphens).

Current:

git clone https://github.com/box-community/box-ai-api-masterclass.git
cd box-ai-api-master-class

Should be:

git clone https://github.com/box-community/box-ai-api-masterclass.git
cd box-ai-api-masterclass

This causes the cd command to fail since the directory doesn't exist with that name.