Add documentation for Bitbucket Discovery processor

Signed-off-by: Mathias Åhsberg <mathias.ahsberg@resurs.se>

docs/integrations/bitbucket/discovery.md

@@ -0,0 +1,43 @@
+---
+id: discovery
+title: Bitbucket Server Discovery
+sidebar_label: Discovery
+description:
+  Automatically discovering catalog entities from repositories in a Bitbucket
+  Server instance
+---
+
+The Bitbucket integration has a special discovery processor for discovering
+catalog entities within a Bitbucket Server instance. The processor will crawl
+the Bitbucket Server instance and register entities matching the configured
+path. This can be useful as an alternative to static locations or manually
+adding things to the catalog.
+
+> Note: The Bitbucket Discovery Processor currently only supports a self-hosted
+> Bitbucket Server, and not the hosted Bitbucket Cloud product.
+
+To use the discovery processor, you'll need a Bitbucket integration
+[set up](locations.md) with a `BITBUCKET_TOKEN`. Then you can add a location
+target to the catalog configuration:
+
+```yaml
+catalog:
+  locations:
+    - type: bitbucket-discovery
+      target: https://bitbucket.mycompany.com/projects/my-project/repos/service-*/catalog-info.yaml
+```
+
+Note the `bitbucket-discovery` type, as this is not a regular `url` processor.
+
+The target is composed of four parts:
+
+- The base instance URL, `https://bitbucket.mycompany.com` in this case
+- The project key to scan, which accepts \* wildcard tokens. This can simply be
+  `*` to scan repositories from all projects. This example only scans for
+  repositories in the `my-project` project.
+- The repository blob to scan, which accepts \* wildcard tokens. This can simply
+  be `*` to scan all repositories in the organization. This example only looks
+  for repositories prefixed with `service-`.
+- The path within each repository to find the catalog YAML file. This will
+  usually be `/catalog-info.yaml` or a similar variation for catalog files
+  stored in the root directory of each repository.