Change name of policy ID in API

In some methods the policy ID parameter was named "instance". It is
changed to "id".

Change-Id: Id267fba84e62a2e6d3ff52ffb3d728561178b337
Issue-ID: NONRTRIC-152
Signed-off-by: elinuxhenrik <henrik.b.andersson@est.tech>
diff --git a/policy-agent/docs/api.yaml b/policy-agent/docs/api.yaml
index 5800f0f..3ea913d 100644
--- a/policy-agent/docs/api.yaml
+++ b/policy-agent/docs/api.yaml
@@ -64,9 +64,9 @@
       produces:
         - '*/*'
       parameters:
-        - name: instance
+        - name: id
           in: query
-          description: instance
+          description: id
           required: true
           type: string
       responses:
@@ -91,9 +91,9 @@
       produces:
         - '*/*'
       parameters:
-        - name: instance
+        - name: id
           in: query
-          description: instance
+          description: id
           required: true
           type: string
         - in: body
@@ -147,9 +147,9 @@
       produces:
         - '*/*'
       parameters:
-        - name: instance
+        - name: id
           in: query
-          description: instance
+          description: id
           required: true
           type: string
       responses:
@@ -281,9 +281,9 @@
       produces:
         - '*/*'
       parameters:
-        - name: instance
+        - name: id
           in: query
-          description: instance
+          description: id
           required: true
           type: string
       responses: