chore(docs):[#408] add introductions to irs recursive and iterative

docs/src/docs/arc42/runtime-view/ess-top-down/irs-recursive.adoc

@@ -0,0 +1,5 @@
+The IRS recursive approach is a decentral approach of retrieving and aggregating data throughout the Catena-X network.
+
+The core functionality is based on notifications which are exchanged between multiple IRS instances. The notifications trigger an investigation on the next level down the supply chain and return aggregated data containing, e.g. simple information about whether a certain BPN is part of the supply chain or not.
+
+Investigations triggered on the next level down the supply chain can trigger further investigations themselves, hence the name _IRS recursive_.

docs/src/docs/arc42/runtime-view/full.adoc

@@ -15,6 +15,7 @@ include::irs-iterative/scenario-4.adoc[leveloffset=+2]
 This section covers the main processes of the IRS in a recursive scenario in a network.
 This recursive scenario is illustrated using the various use cases realized in the scenario.
 
+include::ess-top-down/irs-recursive.adoc[leveloffset=+1]
 include::ess-top-down/ess-top-down.adoc[leveloffset=+1]
 include::ess-top-down/ess-top-down-scenario-1.adoc[leveloffset=+2]
 include::ess-top-down/ess-top-down-scenario-2.adoc[leveloffset=+2]

docs/src/docs/arc42/runtime-view/index.adoc

@@ -15,6 +15,7 @@ This section describes the iterative flow, the main processes of the IRS, and ex
 This section covers the main processes of the IRS in a recursive scenario in a network.
 This recursive scenario is illustrated using the various use cases realized in the scenario.
 
+include::ess-top-down/irs-recursive.adoc[leveloffset=+1]
 - xref:ess-top-down/ess-top-down.adoc[Use Case: ESS (Environmental and Social Standards) Top-Down approach]
 - xref:ess-top-down/ess-top-down-scenario-1.adoc[Scenario 1: Register an Ess-Investigation-Order]
 - xref:ess-top-down/ess-top-down-scenario-2.adoc[Scenario 2: Register an Ess-Investigation-Job]

docs/src/docs/arc42/runtime-view/irs-iterative/irs-iterative.adoc

@@ -1,3 +1,9 @@
+IRS Iterative is the main IRS mode for retrieving data chains throughout the Catena-X network. The core functionality can be summed up in three steps:
+
+1. Start the process with a provided globalAssetId and BPN combination, and required submodels to request.
+2. Retrieve the EDC endpoint for the BPN, search the catalog for the Digital Twin Registry contract Offer and search the DTR for the provided BPN.
+3. Retrieve the relationship submodel for the requested lifecycle and direction and repeat step 1 with the globalAssetIds and BPNs from the relationship submodel linked data until the desired depth is reached or no more relationships could be found.
+
 [plantuml, target=overall, format=svg]
 ....
 include::../../../../uml-diagrams/runtime-view/api-call-asynchrous-sequence.puml[]