docs: Improve docs for `Point` and `Vec2` #566

Job	Run time
cargo check (msrv) (wasm32)	26s
cargo clippy (wasm32)	42s
cargo clippy (windows-latest)	1m 4s
cargo check (msrv) (windows-latest)	53s
cargo clippy (macos-latest)	36s
cargo doc	31s
cargo check (msrv) (macos-latest)	36s
cargo clippy (ubuntu-latest)	41s
cargo fmt	20s
cargo check (msrv) (ubuntu-latest)	28s
cargo test (windows-latest)	46s
cargo test (wasm32)	20s
cargo test (macos-latest)	24s
typos	4s
cargo test (ubuntu-latest)	18s
	8m 9s

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