Add messages to obsolete specs for clarity

[Rowe2ryWA]

Super simple contribution but hopefully a helpful one.

I noticed the obsolete warnings when working in our organization's server repo and it took 15 minutes of research and git blame to find the commit where these were marked obsolete, study the code and determine what I should have been doing instead.

I figured I'd contribute to the project to save the next guy some time. Ardalis is a major backbone of our project so I hope this contribution helps. 🙂

[fiseni]

Hi @Rowe2ryWA,

Thank you for taking the time to contribute here.
I have a suggestion. Would it be possible to change the message as follows? Mentioning ListAsync will just confuse the users.

"Use FirstOrDefaultAsync<T> or SingleOrDefaultAsync<T> instead. The SingleOrDefaultAsync<T> can be applied only to SingleResultSpecification<T> specifications."

[Rowe2ryWA]

Hi @Rowe2ryWA,

Thank you for taking the time to contribute here. I have a suggestion. Would it be possible to change the message as follows? Mentioning ListAsync will just confuse the users.

"Use FirstOrDefaultAsync<T> or SingleOrDefaultAsync<T> instead. The SingleOrDefaultAsync<T> can be applied only to SingleResultSpecification<T> specifications."

Yes, I will make the edits and update the branch.

[fiseni]

Thanks!