docs: add technical notes for catalog documentation

Signed-off-by: Hellgren Heikki <heikki.hellgren@op.fi>

docs/features/software-catalog/life-of-an-entity.md

@@ -125,6 +125,15 @@ all of the processors' contributions to one step are run in the order that the
 processors were registered, then all of their contributions to the next step in
 the same order, and so on.
 
+:::note Technical note
+
+Processors registered from the same catalog module always run
+in the registration order, but this does not apply over multiple catalog modules as
+the order of registration depends on the order in which the modules are loaded
+by the framework.
+
+:::
+
 Each step has the opportunity to optionally modify the entity, and to optionally
 emit other information. For example, the processor might look at information in
 the `spec` field of the entity, and emit relations that correspond to those
@@ -182,6 +191,19 @@ The diagram shows how the stitcher reads from several sources:
 The last part is noteworthy: This is how the stitcher is able to collect all of
 the relation edges, both incoming and outgoing, no matter who produced them.
 
+:::note Technical note
+
+Whether the entity will be stitched depends on the entity hash value,
+which is calculated based on the entity body, relations, errors, referred entities,
+and entity parents after the processing. The hash value changes if any of these components
+change. The hash value is then compared to hash value from the previous processing of the
+entity and if they are different, the entity is stitched again.
+In entity body, changes in array order, for example `metadata.tags`, changes the hash
+value. It is a good idea to monitor the stitched entities count in the catalog as it
+might cause performance issues if the number of entities gets too high.
+
+:::
+
 The stitching is currently a fixed process, that cannot be modified or extended.
 This means that any modifications you want to make on the final result, has to
 happen during ingestion or processing.