Mac installer: add info on how to find and install pre-6.5 CUDA drivers. ...

Mac installer: add info on how to find and install pre-6.5 CUDA drivers.  (This change is included in 7.4.26 Mac release.)

mac_installer/ReadMe.rtf

@@ -19,6 +19,8 @@
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 \cf2 CUDA UPGRADE WARNING\cf0 : Do not upgrade to CUDA 6.5 or later if you have an older NVIDIA GPU with Compute Capability 1.3 or less.  You can check your GPU\'92s Compute Capability at {\field{\*\fldinst{HYPERLINK "https://developer.nvidia.com/cuda-gpus"}}{\fldrslt https://developer.nvidia.com/cuda-gpus}}. \
 \
+You can find older CUDA drivers at {\field{\*\fldinst{HYPERLINK "http://www.nvidia.com/object/mac-driver-archive.html"}}{\fldrslt http://www.nvidia.com/object/mac-driver-archive.html}}. Note: after mounting the downloaded disk image, you may need to control-click on the CUDA installer package to open it.\
+\
 For more options, please see the BOINC Macintosh administrator tools at:\
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 {\field{\*\fldinst{HYPERLINK "http://boinc.berkeley.edu/wiki/Tools_for_Mac_OS_X"}}{\fldrslt \cf0 http://boinc.berkeley.edu/wiki/Tools_for_Mac_OS_X}}\