C++ Learn Docs work

[ronniegeraghty]

• Update the home page for the C++ For Azure Developers page with more content
• updated other parts of learn with link to C++ SDK docs

Update the following pages:

• https://azure.microsoft.com/en-us/downloads/
• https://azure.microsoft.com/en-us/resources/developers/
• https://learn.microsoft.com/en-us/cpp/cloud/cloud-and-web-programming-in-visual-cpp?view=msvc-170
• https://learn.microsoft.com/en-us/cpp/?view=msvc-170