Update Basic example README.md

[rkooo567]

What kind of change does this PR introduce?
I fixed basic_example folder's README.md file because it contains deprecated information.

Does this PR introduce a breaking change?
No, I just changed README.md. But probably some explanation that I wrote might be wrong. Please read through one more time to make sure there's no wrong information.

[AmplabJenkins]

Can one of the admins verify this patch?

[simon-mo]

jenkins test this please
jenkins add to whitelist

[simon-mo]

Jenkins test this please

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1770/
Test FAILed.

[simon-mo]

Jenkins test this please

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1771/
Test FAILed.

[simon-mo]

Jenkins test this please

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1772/
Test FAILed.

[rkooo567]

Why does it keep failing?

[simon-mo]

docker is finicky for some reasons... Let me kick off the retry.

[simon-mo]

jenkins test this please

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
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Test PASSed.