readme: add link to reqwest-chain crate #265

Job	Run time
Rustfmt	8s
Publish dry run	1m 54s
Clippy (opentelemetry_0_13)	51s
Clippy (opentelemetry_0_14)	46s
Clippy (opentelemetry_0_15)	1m 4s
Clippy (opentelemetry_0_16)	48s
Clippy (opentelemetry_0_17)	45s
Clippy (opentelemetry_0_18)	44s
Clippy (opentelemetry_0_19)	59s
Clippy (opentelemetry_0_20)	54s
Docs (opentelemetry_0_13)	49s
Docs (opentelemetry_0_14)	48s
Docs (opentelemetry_0_15)	45s
Docs (opentelemetry_0_16)	54s
Docs (opentelemetry_0_17)	48s
Docs (opentelemetry_0_18)	46s
Docs (opentelemetry_0_19)	39s
Docs (opentelemetry_0_20)	56s
Test Suite (opentelemetry_0_13)	1m 29s
Test Suite (opentelemetry_0_14)	1m 29s
Test Suite (opentelemetry_0_15)	1m 30s
Test Suite (opentelemetry_0_16)	1m 39s
Test Suite (opentelemetry_0_17)	1m 41s
Test Suite (opentelemetry_0_18)	1m 57s
Test Suite (opentelemetry_0_19)	1m 47s
Test Suite (opentelemetry_0_20)	1m 39s
Compiles for the browser (opentelemetry_0_13)	54s
Compiles for the browser (opentelemetry_0_14)	52s
Compiles for the browser (opentelemetry_0_15)	51s
Compiles for the browser (opentelemetry_0_16)	47s
Compiles for the browser (opentelemetry_0_17)	50s
Compiles for the browser (opentelemetry_0_18)	47s
Compiles for the browser (opentelemetry_0_19)	52s
Compiles for the browser (opentelemetry_0_20)	50s
	35m 12s

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