Update README.md

URL of LICENCE and spelling are corrected.

Added string output and sample No.9

• Added string output
• Added sample No.9 (BMI calculation)
• Characters of HTML tags were changed upper to lower
• 5th argument of itemInput constructor was changed (isOmissible -> isOptional)
• 1st argument of anyCalculator constructor was changed (tableID-> id)
• Comments of all sample files were rewritten

Variable names were changed in the sample No.1

• Variable names were changed in the sample No.1 to make them clearer.
• Fixed the README.

README.md is updated.

Descriptions of the samples are added.

The first release

The first release