Update README.md

Author: j2doll

README.md

@@ -7,7 +7,7 @@
 ## Usgae 
 
 ```cpp
-unsigned int debug1 = excelNumber::excelColumnStingToNumber("AB");
-std::string debug2 = excelNumber::convertFromNumberToExcelColumn( debug1 );
+unsigned int debug1 = excelColumnNumber::excelColumnStingToNumber("AB");
+std::string debug2 = excelColumnNumber::convertFromNumberToExcelColumn( debug1 );
 assert( debug2 == "AB" );
 ```