Update base_model_creation documentation in README.md

[satsuta]

base_model_creation supports only a single table and does not handle a list of tables.

Resolves #

Problem

Error in base_model_creation documentation in README.md.

base_model_creation accepts only one table as an argument, but the current README.md states that it receives a list of tables. It appears to have been copy-pasted from another part of the documentation.

I encountered this documentation error multiple times. It is confusing, so I decided to fix it.

This is essentially a cosmetic fix, so I skipped creating an issue.

Solution

Update README.md with accurate information.

Checklist

• This code is associated with an issue which has been triaged and accepted for development.
• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the README.md (if applicable)