website/docs: add scaling page #24471

Job	Run time
lint-golint	1m 27s
test-unittest	2m 19s
ci-outpost-mark	1s
build-container (proxy)	3m 57s
build-binary (proxy, linux, amd64)	2m 2s
build-container (ldap)	2m 59s
build-binary (proxy, linux, arm64)	2m 0s
build-container (radius)	2m 51s
build-binary (ldap, linux, amd64)	2m 4s
build-container (rac)	2m 38s
build-binary (ldap, linux, arm64)	2m 6s
build-binary (radius, linux, amd64)	1m 54s
build-binary (radius, linux, arm64)	1m 51s
build-binary (rac, linux, amd64)	1m 54s
build-binary (rac, linux, arm64)	1m 56s
	31m 59s

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