Fixing the documentation

[arcAman07]

There was an extra parenthesis present "Finding the best model configuration with hyperparameter tuning" section of in "Introduction to Keras for Engineers" which led to the piece of code not executing. Just removed that error which was coming due to an extra parenthesis. The changes have been made to all the files ( ".py, .md and .ipynb").

Signed off Aman Tagging the maintainer for review @fchollet