Update README.md

[abhiksark]

Removed the typo for efficientdet

[pep8speaks]

Hello @abhiksark! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file models/utils.py:

Line 306:80: E501 line too long (115 > 79 characters)
Line 306:116: W291 trailing whitespace
Line 307:80: E501 line too long (115 > 79 characters)
Line 308:80: E501 line too long (115 > 79 characters)
Line 309:80: E501 line too long (115 > 79 characters)
Line 310:80: E501 line too long (115 > 79 characters)
Line 311:80: E501 line too long (115 > 79 characters)
Line 312:80: E501 line too long (115 > 79 characters)
Line 313:80: E501 line too long (115 > 79 characters)
Line 314:80: E501 line too long (115 > 79 characters)

[abhiksark]

Updated the url_map