Add logo and fix the display name of the datadog-service integration in ArtifactHub

[vadasambar]

Problem statement.
Right now, if you search for datadog-service on ArtifactHub, you can see that datadog does not have a logo and the display name shows up as datadog-service instead of Datadog Service

Here's how Prometheus Service looks like:

Describe the solution you'd like

1. Fix the displayName parameter for all versions of datadog-service in the keptn artifacthub repo here
2. Use the following logo from https://www.datadoghq.com/about/resources/
   
   You will have to add a logoUrl parameter in the artifacthub-pkg.yml (for example check this in Prometheus Service). Datadog does not have a logo Url you can use like Prometheus Service. We will have to download the logo, add it under images/ (<- create a new folder here) and use the link like this

TODO

• Raise a PR with the above change
• Ask for review in #keptn-integrations channel (mention @vadasambar so that he can help you out in case of problems)
• Get the PR reviewed (note: you probably won't have the permission to merge the PR in https://github.com/keptn-contrib/artifacthub repo. Ask the reviewer to merge the PR)
• DONE

[vadasambar]

Re-opened because the changes merged in the PR above have not been reflected yet

[tarangverma]

can i take up this issue...

[vadasambar]

Assigned you @tarangverma .

[tarangverma]

keptn-contrib/artifacthub#189