nixd/docs/editor-setup: fix lspconfig link (#607) #3212

Job	Run time
nix-build-develop-clang (none, release, true)	2m 58s
nix-build-develop-gcc (none, release, true)	3m 10s
nix-build-develop-clang (none, release, false)	3m 4s
nix-build-develop-gcc (none, release, false)	3m 7s
nix-build-develop-clang (none, debug, true)	2m 48s
nix-build-develop-gcc (none, debug, true)	2m 58s
nix-build-develop-clang (none, debug, false)	2m 49s
nix-build-develop-gcc (none, debug, false)	3m 4s
nix-build-develop-gcc (address, release, true)	4m 47s
nix-build-develop-gcc (address, release, false)	4m 45s
nix-build-develop-gcc (address, debug, true)	4m 8s
nix-build-develop-gcc (address, debug, false)	4m 2s
nix-build-develop-gcc (undefined, release, true)	4m 1s
nix-build-develop-gcc (undefined, release, false)	4m 14s
nix-build-develop-gcc (undefined, debug, true)	3m 27s
nix-build-develop-gcc (undefined, debug, false)	3m 26s
	56m 48s

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