update readme to remove mention of wasm feature flag #456

Job	Run time
Clippy	3m 1s
Rustfmt	11s
Build Wasm Examples (wasm-yew-minimal)	53s
Build Examples (3d_charts)	28s
Build Examples (basic_charts)	24s
Tests (ubuntu-latest)	1m 50s
Build Examples (custom_controls)	35s
Tests (windows-latest)	4m 8s
Build Examples (financial_charts)	23s
Code Coverage	8s
Tests (macos-latest)	1m 53s
Build Examples (images)	44s
Build Examples (kaleido)	1m 34s
Build Examples (maps)	41s
semver	37s
Build Examples (ndarray)	24s
Build Examples (scientific_charts)	25s
Build Examples (shapes)	24s
Build Examples (subplots)	30s
	19m 13s

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