Add release notes for PR #5781: bevy_reflect: Recursive registration

[MrGVSV]

Fixes #1236

Adds release notes for recursive registration in bevy_reflect.

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There's a small amount of nuance that I chose to gloss over such as why we're doing this instead of using inventory or linkme, or which specific things actually rely on these registrations.

I also chose not to go into detail about how this works under the hood via changes to GetTypeRegistration since most users probably don't even know that trait exists.

I did, however, mention that there is still an opportunity for a footgun if a type that's used on its own (i.e. a component, a resource, etc.) is implicitly registered by another type. This is hopefully a lot less likely to occur than forgetting to register an internal type, but still a possibility. This isn't required information, so we can remove it if its too much or detracts from the rest of the feature, but I thought it might still be good to draw attention to.

Anyways, let me know if there's anything that should be added/changed/removed!

[BD103]

Could you update the title _release-notes.toml to something like "Recursive type registration"? I think the "bevy_reflect" prefix it left over from the PR title.

[BD103]

Reads well and is a good size, looks good! I have one nit about the title, but it's non-blocking. (We'll catch it later in the final pass.)