Load mermaid asynchronously in docs #16827

Job	Run time
Event File	3s
Build Erlang/OTP (64-bit)	5m 38s
Build Erlang/OTP (iOS)	6m 46s
Build Erlang/OTP (macOS)	8m 36s
Build Erlang/OTP (Types and Flavors)	8m 27s
Build Erlang/OTP (Windows)	13m 7s
Build Erlang/OTP (32-bit)	10m 18s
Build and check documentation	5m 18s
Build Erlang/OTP (cross-compile)	15m 6s
Run static analysis	6m 31s
Build Erlang/OTP (clang)	6m 15s
Test Erlang/OTP (emulator)	48m 41s
Test Erlang/OTP (debug)	5m 2s
Release Erlang/OTP	0s
Test Erlang/OTP (system)	13m 59s
	2h 33m 47s

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