C++: Added ordered list under the heading Goals of the Style Guide and add …

[Mustafa-Hassan2001]

…content about scoping under it's heading in cppguide.html file

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Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[MohsinMalik2]

I'm attempting this enhancement as I've signed CLA and it seems to be a good enhancement with slight content changes.