contrib: add `release.md` #965

Job	Run time
Build (stable, -p nostr)	1m 27s
Format	6s
Build (stable, -p nostr --no-default-features --features alloc)	1m 3s
Build no_std (nightly)	1m 43s
Build (stable, -p nostr --no-default-features --features "alloc all-nips")	37s
Build WASM (stable, -p nostr)	35s
Build (stable, -p nostr --features blocking)	2m 2s
Build WASM (stable, -p nostr-sdk)	36s
Build (stable, -p nostr-sdk)	2m 21s
Build WASM (stable, -p nostr-js)	26s
Build (stable, -p nostr-sdk --no-default-features)	1m 24s
Build WASM (1.64.0, -p nostr)	5m 16s
Build (stable, -p nostr-sdk --features blocking)	2m 31s
Build WASM (1.64.0, -p nostr-sdk)	4m 47s
Build (stable, -p nostr-ffi)	2m 16s
Build (stable, -p nostr-sdk-ffi)	2m 47s
Build WASM (1.64.0, -p nostr-js)	5m 18s
Build (1.64.0, -p nostr)	6m 59s
Build (1.64.0, -p nostr --no-default-features --features alloc)	4m 45s
Build (1.64.0, -p nostr --no-default-features --features "alloc all-nips")	5m 38s
Build (1.64.0, -p nostr --features blocking)	6m 0s
Build (1.64.0, -p nostr-sdk)	6m 51s
Build (1.64.0, -p nostr-sdk --no-default-features)	5m 37s
Build (1.64.0, -p nostr-sdk --features blocking)	7m 45s
Build (1.64.0, -p nostr-ffi)	6m 1s
Build (1.64.0, -p nostr-sdk-ffi)	8m 20s
	1h 33m 11s

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