wip update api docs

Author: andrepapoti

docs/api/schemas/patchwork.j2

@@ -1250,9 +1250,13 @@ paths:
         - series
 {% if version >= (1, 4) %}
     patch:
-      summary: Link both series.
+      summary: Link series to set a relationship between them
       description: |
-        Apply a partial update to a Series
+        Apply a partial update to a Series, where only a few fields of the model are allowed:
+        - previous_series: Set the provided series as coming before the one specified by the id;
+        - subsequent_series: Set the provided series as coming after the one specified by the id;
+        - required_series: Set the provided series as requirements for one specified by the id;
+        - required_by_series: Set the series specified by the id as a requirement for the provided ones.
       operationId: series_link
       responses:
         '200':
@@ -2734,8 +2738,29 @@ components:
           readOnly: true
           uniqueItems: true
 {% if version >= (1, 4) %}
-        related_series:
-          title: Related series
+        previous_series:
+          title: Previous series
+          type: array
+          items:
+            $ref: '#/components/schemas/Series'
+          readOnly: true
+          uniqueItems: true
+        subsequent_series:
+          title: Subsequent series
+          type: array
+          items:
+            $ref: '#/components/schemas/Series'
+          readOnly: true
+          uniqueItems: true
+        required_series:
+          title: Required series
+          type: array
+          items:
+            $ref: '#/components/schemas/Series'
+          readOnly: true
+          uniqueItems: true
+        required_by_series:
+          title: Required by series
           type: array
           items:
             $ref: '#/components/schemas/Series'