Clarify add-ons installation instructions

[p-null]

Summary

here, it says users can install add-ons, but it's unclear what should happen after the installation. do i need to configure anything for nebula to work with these add-ons?

Add more detailed documentation on how to configure Nebula to work with these add-ons, how these add-ons work with Nebula, what each of them is for?

[wey-gu]

Dear @p-null ,
Thank you! Sorry for confusing you on the add-ons doc, we for sure will polish it to avoid any confusion.

"do I need to configure anything for nebula to work with these add-ons":

Apart from the volume provider, which should be reflected in CRD: nebulaCluster::<graph_or_meta_or_storage>:: storageClaim:: storageClassName, the other ones now requires no configurations(and they are mandatory actually, we should have put this clear).

Add more detailed documentation on how to configure Nebula to work with these add-ons, how these add-ons work with Nebula, what each of them is for?

Thank you, Peterson, now maybe CRD sample is somewhat self-explanation but we will for sure do revisit and make things more clear for users to a quick start and remove the confusion on add-ons(at least which are mandatory, which are optional)

cc @MegaByte875 @veezhang @kqzh

[p-null]

Thanks for following up on this.

I understand examples are helpful but that just brings too much frictions by reading these examples to understand what I want.

I would suggest provide a api like readme for each of the parameters.

Regarding the specific examples you gave, I still don't have answers for following questions:
"What should I configure for Nebula to use a existing component, like cert-manager?"
"What is each of the component used for?"

I don't need the answer right here, I am just suggesting a better way to document things.

Love to see improvements on the documentation. Thanks!

[MegaByte875]

@p-null Thanks for your suggestions. I will update docs recently.

[MegaByte875]

https://github.com/vesoft-inc/nebula-operator/blob/v0.8.0/doc/user/add-ons.md @p-null