Recommend to have why in PR desc

[viveksinghggits]

Summary

Adding why a particular PR is needed, is important in PR desc. This help reviewers understand the PR better.
This PR encourages authors to do that by updating the PR template.

Proof of Work

NA

[github-actions]

⚠️ (this preview might not be accurate if the PR is not rebased on current master branch)

MCK 1.6.0 Release Notes

New Features

• MongoDBCommunity: Added support to configure custom cluster domain via newly introduced spec.clusterDomain resource field. If spec.clusterDomain is not set, environment variable CLUSTER_DOMAIN is used as cluster domain. If the environment variable CLUSTER_DOMAIN is also not set, operator falls back to cluster.local as default cluster domain.
• Helm Chart: Introduced two new helm fields operator.podSecurityContext and operator.securityContext that can be used to configure securityContext for Operator deployment through Helm Chart.

Bug Fixes

• Fixed parsing of the customEnvVars Helm value when values contain = characters.

[Julien-Ben]

As a template, I think it should be much more concise. The first line is enough IMO.

Jira tickets are already mentioned in the Checklist

[anandsyncs]

I have a similar question, is this a substitution for absence of JIRA ticket in the PR?

[viveksinghggits]

So the point that @Julien-Ben raised is different from the question that you have @anandsyncs.

@Julien-Ben's point was we don't have to mention This is not a replacement for creating jira tickets. this line because we already have have a check box in our PR template checklist for the jira ticket and that would mean a jira ticket is required.

And I think what you are asking is, if you mention why in PR desc, do you not have to create jira ticket anymore. And we knew that people might get into that confusion, that's why I explicitly mentioned, having why in PR desc doesnt mean that you don't have to create the respective jira ticket.

[lsierant]

+1, let's keep "Enter your PR summary here. Try to emphasize on WHY this change is needed, followed by what's being done in the PR."
the rest is a bit obvious