Add a few notes to Sprite3D's documentation #239

Job	Run time
📊 Static checks / Code style, file formatting, and docs	3m 7s
🐧 Linux / Editor w/ Mono (target=editor)	35m 12s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	36m 47s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	32m 6s
🌐 Web / Template (target=template_release)	1m 16s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	6m 55s
🤖 Android / Template (target=template_release)	3m 21s
🐧 Linux / Template w/ Mono (target=template_release)	1m 56s
🍎 macOS / Editor (target=editor, tests=yes)	3m 49s
🐧 Linux / Minimal template (target=template_release, everything disabled)	2m 4s
🍎 macOS / Template (target=template_release)	3m 49s
🏁 Windows / Editor (target=editor, tests=yes)	41m 24s
🏁 Windows / Template (target=template_release)	6m 34s
🍏 iOS / Template (target=template_release)	2m 48s
🪲 Godot CPP / Build and test Godot CPP	6m 46s
	3h 7m 54s

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