release notes stuff and /usr/local/cuda/lib/ and ldconfig

I believe that I have solved the problem of

error while loading shared libraries: cannot open shared object file: No such file or directory

I found the answer in the NVIDIA forums. I added

/usr/local/cuda/lib to and the ran ldconfig as root.

Now every posting in the respond section says that this is discussed in the release notes. I want to know where is it discussed in the release notes.

I already have the LD_LIBRARY_PATH as (/usr/local/cuda/lib) so why or why repeat it? What is the significance of and thus why add this path to it that file. Also, when this is done
why run ldconfig? I think if i could just read about in the release notes that would be answer all or most of my questions. I am looking to learn more about this. i am new to Linux. This is the first time that I have seen this problem and
I want why I did what I did.

I spent a lot of time on the one. Help understand the error of my ways.