docs: Added requests body for 'Password for User' and 'Permissions' in the admin api documentation

docs/sources/http_api/admin.md

@@ -237,12 +237,14 @@ Change password for specific user
     Accept: application/json
     Content-Type: application/json
 
+    {"password":"userpassword"}
+
 **Example Response**:
 
     HTTP/1.1 200
     Content-Type: application/json
 
-    {"password":"userpassword"}
+    {"message": "User password updated"}
 
 ## Permissions
 
@@ -254,6 +256,8 @@ Change password for specific user
     Accept: application/json
     Content-Type: application/json
 
+    {"isGrafanaAdmin": true}
+
 **Example Response**:
 
     HTTP/1.1 200