Standardize readme shield badges

[MO2k4]

Description

Standardize readme shield badges

Issue reference

We strive to have all PRs being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #1023

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• The quickstart code compiles correctly
• You've tested new builds of the quickstart if you changed quickstart code
• You've updated the quickstart's README if necessary
• If you have changed the steps for a quickstart be sure that you have updated the automated validation accordingly. All of our quickstarts have annotations that allow them to be executed automatically as code. For more information see mechanical-markdown. For user guide with examples see Examples.

[marcduiker]

@MO2k4 thanks for picking this up again
Could you sign off your commit? See the DCO check for more info.

[MO2k4]

@marcduiker done

[marcduiker]

Thank you @MO2k4!

@dapr/approvers-quickstarts this is only a change in the README, validation workflows can be skipped on this PR.