Update hybrid cache documentation on tag removal

[tdykstra]

Clarifies that RemoveByTagAsync performs logical invalidation rather than physical deletion, and explains what "treated as a cache-miss" means in practice.

Fixes #36757

Why this fits:

It stays in the user-doc / conceptual lane.
It explains “treated as a cache-miss” more clearly.
It avoids getting too deep into implementation internals.
It matches the existing recommendation to revise the paragraph at roughly lines 120–123 in hybrid.md.

Summary

Clarifies the "Remove cache entries by tag" section in the HybridCache article.
The previous wording ("treated as a cache-miss") was unclear about how tag invalidation works in practice. This update explains that invalidation is a logical operation rather than a physical deletion, and that older entries are ignored on read rather than actively removed.

What changed

• Rewrote the explanatory paragraph in `aspnetcore0/performance/caching/hybrid.md
• Clarified that:
• RemoveByTagAsync does not delete entries from L1 or L2
• invalidation works as an "ignore older entries" rule
• stale entries are treated as cache misses and refreshed

Why

Addresses confusion raised in #36757 about:

• how invalidation works across processes
• what "treated as a cache-miss" means
• whether the factory runs repeatedly after invalidation

Notes

Kept the explanation conceptual (user-doc level), avoiding low-level implementation details.

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Internal previews

📄 File	🔗 Preview link
aspnetcore/performance/caching/hybrid.md	HybridCache library in ASP.NET Core

[wadepickett]

These two duplicate paragraphs to the new text above would be removed.

[wadepickett]

Few items to fix.

[wadepickett]

@tdykstra,
Approved. I made some very minor suggestions to consider.

[wadepickett]

Approved. (unblocking merge since it blocks if any commits happen after a review approval now).