Add documentation note on Object's boolean context #775

Job	Run time
📊 Static checks / Code style, file formatting, and docs	1m 4s
🤖 Android / Editor (target=editor)	24m 29s
🤖 Android / Template arm32 (target=template_release, arch=arm32)	16m 23s
🍏 iOS / Template (target=template_release)	11m 28s
🤖 Android / Template arm64 (target=template_release, arch=arm64)	16m 57s
🐧 Linux / Editor w/ Mono (target=editor)	40m 17s
🍎 macOS / Editor (target=editor, tests=yes)	28m 58s
🐧 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)	46m 2s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	25m 30s
🍎 macOS / Template (target=template_release)	21m 34s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	35m 18s
🌐 Web / Template w/o threads (target=template_release, threads=no)	25m 51s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	30m 53s
🐧 Linux / Template w/ Mono (target=template_release)	26m 39s
🏁 Windows / Editor (target=editor, tests=yes)	48m 12s
🐧 Linux / Minimal template (target=template_release, everything disabled)	14m 53s
🏁 Windows / Template (target=template_release)	35m 8s
🪲 Godot CPP / Build and test Godot CPP	7m 49s
	7h 37m 25s

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