update README.md

Author: stoeckerb

README.md

@@ -4,3 +4,10 @@ Deployment
 
 1) in application subdirectory "sqldrivers" qsqlmysql.dll (Release) / qsqlmysqld.dll (Debug)
 2) the MySQL library itself libmysql.dll
+
+ 
+Building hints
+
+- Make sure you link against the official MySQL C Connector v6.1 (not C++): https://downloads.mysql.com/archives/c-c/?version=6.1.2&os=src
+- The .pro file from this repository by default expects the contents of the zip file from mysql.com to be in the same base directory as the sql driver project
+	e.g. D:\qt\src\sqldrivers is the sql driver project dir and D:\qt\src\mysql-connector-c-6.1.2-win32 is the MySQL connector library directory, so that there are D:\qt\src\mysql-connector-c-6.1.2-win32\include and \lib subdirs