udpate quick start for tfjobs

[jinchihe]

The quick start for tfjobs is out of date, The current versions of the TF operator is v1beta1, but the quick start is still for v1alpha2, that cannot be executed in kubeflow 0.4, and some link is not reasonable.

The PR is to update the quick start for v1beta1, and correct a link and sample outputs. Thanks.

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This change is 

[jinchihe]

/assign @ScorpioCPH

[coveralls]

Coverage remained the same at 76.744% when pulling 3763202 on jinchihe:udpate_quick_start_for_tf into 6f74850 on kubeflow:master.

[jinchihe]

/assign @gaocegege

Could you please take a look or assign someone? Thanks.

[johnugeorge]

Current version is v1beta2 and v1beta1 configs are also supported. I see that v1beta2 examples are not added though.
Related: #943

[jinchihe]

Current version is v1beta2 and v1beta1 configs are also supported. I see that v1beta2 examples are not added though.
Related: #943

Thanks @johnugeorge, I updated the quick start to mention v1beta2. But I think we can just show v1beta1 as previous behavior, since just have example for v1beta1 under examples. Comments?

[johnugeorge]

Sounds good

[johnugeorge]

/retest

[johnugeorge]

/lgtm

[johnugeorge]

/approve

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