Refactor protocol Validation and Application documentation to integrate Pipelining up to Kathmandu

We propose to refactor the protocol overview section, adding a new validation section from the protocol perspective, focusing on pipelined validation.

Pipelined validation up-to Katmandu

• document operations and validation passes (Implemented in !5490 (merged))
• document manager operations properly (Implemented in !5490 (merged))
• document operation batches' semantics (cf. #3111 (closed)) (Implemented in !5490 (merged))
• document pipelined validation of manager operations (Implemented in !5490 (merged))
• document non-pipelined validation of other validation passes
• harmonize precheck plugin documentation for Kathmandu wrt validation section.
• document pipelined application of manager operations (Implemented in !5490 (merged))
• document validation modes (Implemented in !5490 (merged))
• backport to Kathmandu doc (Implemented in !5490 (merged))
• backport to Lima doc (Implemented in !5490 (merged))