Update 03-Container-Test.md

[aabdullin]

No description provided.

[shawnhankim]

• Thanks @aabdullin for this PR to try fixing it.
• But, the root directory is ./nginx-oidc-onelogin so ./docker/build-context/ssl/ makes more sense, and make start also can be run in the directory of ./nginx-oidc-onelogin.
• If you would like to add more instructions for customers' convenience, then you can add some comments like prerequisite: the working directory is ./nginx-oidc-onelogin.