Adding docs on how to authenticate with prometheus to nifi 2.x.x metrics #2339

Job	Run time
Run Cargo Deny (bans licenses sources)	21s
Run Cargo Deny (advisories)	25s
Run Cargo Udeps	1m 47s
Decide if Helm charts are pushed to the helm repository based on action trigger	4s
Run Rustfmt	18s
Run Clippy	34s
Run Cargo Tests	32s
Run RustDoc	1m 19s
Check if committed Helm charts are up to date	45s
Check if committed README is the one we would render from the available parts	32s
All tests passed	3s
Package Charts, Build Docker Image and publish them - ubuntu-latest	17m 26s
Package Charts, Build Docker Image and publish them - ubicloud-standard-8-arm	12m 4s
Build and publish manifest list	49s
Run the OpenShift Preflight check on the published images	17s
	37m 16s

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