Integrate Pipelines Concept Definition with the respective expanded sections

We have a section with definitions for the core components of Pipelines here: https://docs.openshift.com/container-platform/4.6/pipelines/understanding-openshift-pipelines.html#op-pipelines-concepts_understanding-openshift-pipelines

Just below that we have detailed information about the same components here: https://docs.openshift.com/container-platform/4.6/pipelines/understanding-openshift-pipelines.html#op-detailed-concepts

We need to consolidate these two sections into one holistic conceptual information for each component. Add the definitions to the detailed concept level modules if it adds extra information, if it is repetitive remove the information. If there are definitions only but no corresponding detailed section, you may want to retain those definitions in separate modules. Also confirm with SMEs/Souvik/myself if some of the concepts are redundant/deprecated.