BaseTools: Mentioned get_vsvars.bat at ReadMe
BaseTools: Mentioned get_vsvars.bat at ReadMe

When someone doesn't know where to find or what to do with
vsvars32.bat, get_vsvars.bat can be used.

CC: Yonghong Zhu <78d981fe33a016071af5222c56d5cf77f30fb0b2@intel.com>
CC: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Peter Kirmeier <8f7335355e8bf024b052c8240535a4b736362ea0@freenet.de>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2