fix some build errors

Author: mongoKart

source/aggregation/pipeline-stages.txt

@@ -34,29 +34,29 @@ method. See the following examples to learn more about each of these approaches.
 .. tabs::
 
   .. tab:: Create a Pipeline
-    :tabid: pipeline-definition
+     :tabid: pipeline-definition
 
-      .. code-block:: javascript
+     .. code-block:: javascript
 
-         // Defines the aggregation pipeline
-         const pipeline = [
-           { $match: { ... } },
-           { $group: { ... } }
-         ];
+        // Defines the aggregation pipeline
+        const pipeline = [
+          { $match: { ... } },
+          { $group: { ... } }
+        ];
 
-         // Executes the aggregation pipeline
-         const results = await collection.aggregate(pipeline);
+        // Executes the aggregation pipeline
+        const results = await collection.aggregate(pipeline);
 
   .. tab:: Direct Aggregation
-    :tabid: pipeline-direct
+     :tabid: pipeline-direct
 
-    .. code-block:: javascript
+     .. code-block:: javascript
 
-       // Defines and executes the aggregation pipeline
-       const results = await collection.aggregate([
-         { $match: { ... } },
-         { $group: { ... } }
-       ]);
+        // Defines and executes the aggregation pipeline
+        const results = await collection.aggregate([
+          { $match: { ... } },
+          { $group: { ... } }
+        ]);
 
 Aggregation Stage Methods
 -------------------------