add Crud link

Author: rustagir

source/fundamentals.txt

@@ -14,7 +14,7 @@ Fundamentals
    Stable API </fundamentals/stable-api>
    Databases & Collections </fundamentals/databases-collections>
    Data Formats </fundamentals/data-formats>
-   CRUD Operations /fundamentals/crud
+   CRUD Operations </fundamentals/crud>
    Builders </fundamentals/builders>
    Aggregation </fundamentals/aggregation>
    Aggregation Expressions </fundamentals/aggregation-expression-operations>