Add docs for the new validateLocationsExist option

Signed-off-by: Nikolas Skoufis <nskoufis@seek.com.au>

docs/integrations/github/discovery.md

@@ -96,6 +96,13 @@ catalog:
           topic:
             include: ['backstage-include'] # optional array of strings
             exclude: ['experiments'] # optional array of strings
+      validateLocationsExist:
+        organization: 'backstage' # string
+        catalogPath: '/catalog-info.yaml' # string
+        filters:
+          branch: 'main' # string
+          repository: '.*' # Regex
+        validateLocationsExist: true # optional boolean
       enterpriseProviderId:
         host: ghe.example.net
         organization: 'backstage' # string
@@ -110,7 +117,8 @@ This provider supports multiple organizations via unique provider IDs.
 - **`catalogPath`** _(optional)_:
   Default: `/catalog-info.yaml`.
   Path where to look for `catalog-info.yaml` files.
-  You can use wildcards - `*` or `**` - to search the path and/or the filename
+  You can use wildcards - `*` or `**` - to search the path and/or the filename.
+  Wildcards cannot be used if the `validateLocationsExist` option is set to `true`.
 - **filters** _(optional)_:
   - **branch** _(optional)_:
     String used to filter results based on the branch name.
@@ -131,6 +139,12 @@ This provider supports multiple organizations via unique provider IDs.
   If you want to add multiple organizations, you need to add one provider config each.
 - **host** _(optional)_:
   The hostname of your GitHub Enterprise instance. It must match a host defined in [integrations.github](locations.md).
+- **validateLocationsExist** _(optional)_:
+  Whether to validate locations that exist before emitting them.
+  This option avoids generating locations for catalog info files that do not exist in the source repository.
+  Defaults to `false`.
+  Due to limitations in the GitHub API's ability to query for repository objects, this option cannot be used in 
+  conjunction with wildcards in the `catalogPath`.
 
 ## GitHub API Rate Limits