add documentation for RecordSourceProxy #8270

Job	Run time
Compiler output check (ubuntu-latest)	4m 22s
Build Rust Compiler (ubuntu-latest)	4m 40s
Compiler output check (macos-latest)	3m 21s
Rust Tests (ubuntu-latest)	4m 29s
Build Rust Compiler (ubuntu-latest)	5m 34s
Rust Tests (macos-latest)	3m 24s
Rust Tests (windows-latest)	7m 19s
Build Rust Compiler (macos-latest)	2m 51s
JS Lint	54s
JS Tests (Node 18.x)	1m 34s
JS Tests (Node 20.x)	1m 24s
Build Rust Compiler (macos-latest)	3m 59s
Build Rust Compiler (windows-latest)	8m 21s
Rust Lint	26s
Flow Typecheck	40s
VSCode Extension Lint	21s
Publish to NPM	1m 29s
	55m 8s

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