Revert "Revert "Revert "Added GitHub URL"""

This reverts commit f1a08c901d2270edc8627e774383ebce6c770188.
C Program to convert Binary number to Decimal

C Program to convert binary number into its equivalent Decimal. In this
program we first check the entered number is binary or not then, we
convert the binary number to decimal number, for example 0111 to 7.