refactor: invalid username error message to clarify the accepter format

[PredictiveManish]

https://github.com/dailydotdev/docs/issues/400

This issue is solved in this PR.

This PR changes the error message seen by user during registering and having their username.

• When people select/enter their username- It was showing username is invalid but not showing what is the requirements.
• This issue is raised in the docs repo of daily.dev.

Summary-

This issue will help users to find out name format so that they can easily register and make their account freely.

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[sshanzel]

I think your previous PR was better. Let's reopen that instead and I will have it merged.

For reference: https://github.com/dailydotdev/apps/pull/3674

[PredictiveManish]

I think your previous PR was better. Let's reopen that instead and I will have it merged.

For reference: #3674

It was deleted that's why I opened this.

[sshanzel]

Yeah, you closed it, but it was actually a valid one.

Sorry, I mean this one https://github.com/dailydotdev/apps/pull/3661

[PredictiveManish]

Yeah, you closed it, but it was actually a valid one.

Sorry, I mean this one #3661

I got your point but I deleted the previously forked repository and now I am unable to access that PR.