Add downloads badge to readme #4504

Job	Run time
Prepare	1m 4s
Build-And-Test-Web	3m 41s
Run unit tests parallel (1)	54s
Build-And-Test-Server (Simple integration tests)	44m 31s
Run unit tests parallel (2)	27m 37s
Build-And-Test-Server (Reducer integration tests)	15m 43s
Run unit tests parallel (3)	5m 56s
Build-And-Test-Server (DEX integration tests)	17m 36s
Build-And-Test-Server (DEX integration test with proofs)	16m 33s
Run unit tests parallel (4)	20m 49s
Build-And-Test-Server (Voting integration tests)	6m 25s
Run unit tests parallel (5)	14m 4s
Build-And-Test-Server (Verification Key Regression Check 1)	33m 31s
Run unit tests parallel (6)	8m 29s
Build-And-Test-Server (Verification Key Regression Check 2)	50m 59s
Run unit tests parallel (7)	15m 57s
Build-And-Test-Server (CommonJS test)	1m 26s
Run unit tests parallel (8)	2m 24s
Build-And-Test-Server (Unit tests)	1s
Release-on-NPM	0s
Release-mina-signer-on-NPM	0s
	4h 47m 40s

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