enhanced documentation, adding the "condition" for POST search

Signed-off-by: Thomas Jäckle <thomas.jaeckle@beyonnex.io>

documentation/src/main/resources/openapi/ditto-api-2.yml

@@ -6907,6 +6907,15 @@ paths:
 
                     The deprecated paging option `limit` may not be combined with the other paging options `size` and `cursor`.
                   type: string
+                condition:
+                  description: |-
+                    Similar to the `filter`, a `condition` may be passed to ensure strong consistency when querying things.
+
+                    This `condition` has the same syntax and semantics than the `filter` - it is however applied on the matched things
+                    selected by the `filter` - on their current state.
+
+                    So combining this together with `filter` can provide strong consistency when performing a search.
+                  type: string
             encoding:
               filter:
                 style: form

documentation/src/main/resources/openapi/sources/paths/search/things.yml

@@ -173,6 +173,8 @@ post:
               $ref: '../../schemas/properties/thingFieldsProperty.yml'
             option:
               $ref: '../../schemas/properties/optionProperty.yml'
+            condition:
+              $ref: '../../schemas/properties/searchConditionProperty.yml'
         encoding:
           filter:
             style: form

documentation/src/main/resources/openapi/sources/schemas/properties/searchConditionProperty.yml

@@ -0,0 +1,19 @@
+# Copyright (c) 2023 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Eclipse Public License 2.0 which is available at
+# http://www.eclipse.org/legal/epl-2.0
+#
+# SPDX-License-Identifier: EPL-2.0
+#filter:
+description: |-
+    Similar to the `filter`, a `condition` may be passed to ensure strong consistency when querying things.
+    
+    This `condition` has the same syntax and semantics than the `filter` - it is however applied on the matched things
+    selected by the `filter` - on their current state.
+    
+    So combining this together with `filter` can provide strong consistency when performing a search.
+type: string