Improved docs for "sample-apps/blank-go"

[kakakakakku]

Hi,

Thank you for creating the sample Go project blank-go that is easy to learn from!

I made some improvements that I think will be helpful.

• Added .gitignore.
• Added notes on using Apple Silicon.
  • This error may occur when using a Mac with Apple Silicon.

{"errorMessage":"fork/exec /var/task/main: exec format error","errorType":"PathError"}

Thank you!