Document MaxCacheItems for Apple, Java and .NET

[philipphofmann]

Add docs for MaxCacheItems for Java, Apple, and .NET, when these issues are closed getsentry/sentry-cocoa#899, getsentry/sentry-dotnet#736.

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Accepted, I will leave it alone ... forever!

---

"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[philipphofmann]

Only enable this for Apple once 7.0.0 GA is released. I added this to #3307 so we can close this issue.