Add docker-compose setup for local development

[sureshdsk]

• added docker-compose setup for local development
• updated readme

[lqmanh]

Thank you for your PR and sorry for my late reply.
I am just not sure if this is really necessary, as this docker-compose thing is related to Postgrest side. It is only useful if we use it in the testing pipeline.

[sureshdsk]

I was trying to contribute to postgrest-py, Setting up local dev environment for development and testing was little bit hard. So I prepared this docker-compose setup as a first thing. It becomes so much easier to getstarted without fiddling around postgres and posgrest setup. I think we can also use this for running tests.

[lqmanh]

I understand.
I may keep this PR open in case we really need it later, but cannot merge for now.

[lqmanh]

@sureshdsk Thank you for your contribution. I think it's OK to merge this now.

[sureshdsk]

@lqmanh Thanks