docs: Add docs on how use custom Python processors #2020

Job	Run time
Check if committed README is the one we would render from the available parts	20s
Check if committed Helm charts are up to date	43s
Run Cargo Deny (advisories)	1m 23s
Run Clippy	4m 23s
Run Cargo Deny (bans licenses sources)	39s
Run RustDoc	4m 43s
Run Rustfmt	23s
Run Cargo Tests	48s
Run Cargo Udeps	1m 42s
Select target helm repository based on action trigger	1s
All tests passed	1s
Package Charts, Build Docker Image and publish them - ubuntu-latest	11m 45s
Package Charts, Build Docker Image and publish them - ubicloud-standard-8-arm	10m 32s
Build and publish manifest list	53s
Run the OpenShift Preflight check on the published images	15s
	38m 31s

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