SBSA-QEMU: Address user comments

The following is a list of changes:

• The current InstallGo.sh exports the path to Go by writing it to ~/.bash_profile and then sourcing this file. Since not all Linux distributions have a ~/.bash_profile, we just export to PATH in ImageBuildscript.sh. In addition, the README now explains how to install Go to a different location.
• In README, the machine specifications for the native build list 251 GB RAM instead of 256 GB RAM. This is fixed.
• The current instructions for compiling QEMU from source don't list the necessary packages. This is added to README. In addition, the README now explains how to install QEMU to a different location.
• There was some confusion in the current instructions on how to deal with the patches that are located in non-standard locations. This can happen, for example, when the user does not clone the entire repository, but instead downloads files individually. A clarification is added to README.
• The current Run.sh does not explicitly specify the format of firmware images, which results in a warning when QEMU starts. This is now fixed.