docs: fix description of flow control (#11612)
docs: fix description of flow control (#11612)


Risk Level: Low
Docs Changes: This pull request fixes typos and the descriptions about calling readDisable on high/low watermarks.

Signed-off-by: tomocy <c6bb0fc29200b729e40fc1633245434da261d392@gmail.com>
envoyproxy/envoy,lyft/envoy,lyft/envoy,envoyproxy/envoy-wasm,lyft/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,lizan/envoy,lyft/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,lyft/envoy,lyft/envoy,lizan/envoy,envoyproxy/envoy-wasm,lizan/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy