Update xirr.mdx

Removed a confusing code comment

Author: morgan-at-cube

docs/pages/product/data-modeling/recipes/xirr.mdx

@@ -54,8 +54,6 @@ cubes:
         sql: payment
         type: number
 
-    # Everything below this line is only needed for querying
-    # pre-aggregations in Cube Store
       - name: date__day
         sql: "{date.day}"
         type: time
@@ -101,8 +99,6 @@ cube(`payments`, {
       type: `number`
     },
 
-    // Everything below this line is only needed for querying
-    // pre-aggregations in Cube Store
     date__day: {
       sql: `${CUBE.date.day}`,
       type: `time`
@@ -198,4 +194,4 @@ All queries above would yield the same result:
 [ref-query-wpp]: /product/apis-integrations/queries#query-with-post-processing
 [ref-query-regular]: /product/apis-integrations/queries#regular-query
 [link-tesseract]: https://cube.dev/blog/introducing-next-generation-data-modeling-engine
-[ref-multi-stage-calculations]: /product/data-modeling/concepts/multi-stage-calculations
+[ref-multi-stage-calculations]: /product/data-modeling/concepts/multi-stage-calculations