Update constructors.md: Incorrect list order

Added two spaces in first element </details> 
It was not containing indented lines
Before:
     <details>
</details>
After:
    <details>
    </details>

content/types/matrices/constructors.md

@@ -18,7 +18,7 @@ Matrices have three kinds of constructors:
 
    `mat3x2f()` constructs a `mat3x2f` with zero-values for each of the elements.
 
-  </details>
+   </details>
 
 1. Column-wise constructor: {{< mat "mat(C)x(R)<f32>(column_0, column_1, ...)" >}}