fix: allow to set maxDepth: 0 for join fields, improve join field JSDoc (#10336)

Allows to set `maxDepth: 0` for join fields and improves JSDoc about
`maxDepth`, adds tests to confirm that
https://github.com/payloadcms/payload/issues/10243 is not an issue, but
just happens because the default `maxDepth` is `1`.

test/joins/config.ts

@@ -168,6 +168,45 @@ export default buildConfigWithDefaults({
         },
       ],
     },
+    {
+      slug: 'depth-joins-1',
+      fields: [
+        {
+          name: 'rel',
+          type: 'relationship',
+          relationTo: 'depth-joins-2',
+        },
+        {
+          name: 'joins',
+          type: 'join',
+          collection: 'depth-joins-3',
+          on: 'rel',
+          maxDepth: 2,
+        },
+      ],
+    },
+    {
+      slug: 'depth-joins-2',
+      fields: [
+        {
+          name: 'joins',
+          type: 'join',
+          collection: 'depth-joins-1',
+          on: 'rel',
+          maxDepth: 2,
+        },
+      ],
+    },
+    {
+      slug: 'depth-joins-3',
+      fields: [
+        {
+          name: 'rel',
+          type: 'relationship',
+          relationTo: 'depth-joins-1',
+        },
+      ],
+    },
   ],
   localization: {
     locales: ['en', 'es'],