[YUNIKORN-2049] Fix incorrect placement rule examples

[brandboat]

What is this PR for?

There are some useful placement rule examples under https://github.com/apache/yunikorn-k8shim/tree/master/deployments/examples/placements

while there are some incorrect settings in them:

• queue.yaml should be queues.yaml
• label yunikorn.apache.org/username is legacy and should be switched to annotation yunikorn.apache.org/user.info

Correct me if I'm wrong, the backward compatibility for the label yunikorn.apache.org/username seems broken. The placement rules examples in the link mentioned will not work with the label, but will only be effective with the annotation (i.e., yunikorn.apache.org/user.info).

What type of PR is it?

• - Documentation

Todos

N/A

What is the Jira issue?

https://issues.apache.org/jira/browse/YUNIKORN-2049

How should this be tested?

N/A

Screenshots (if appropriate)

N/A

Questions:

N/A

[codecov]

Codecov Report

Merging #691 (a7479e9) into master (7b08702) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #691   +/-   ##
=======================================
  Coverage   71.81%   71.81%           
=======================================
  Files          51       51           
  Lines        8105     8105           
=======================================
  Hits         5821     5821           
  Misses       2084     2084           
  Partials      200      200           

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[wilfred-s]

LGTM