Move "River crossing puzzle" into tutorial folder

- Update links
- Delete "QL etudes" folder

Author: Shati Patel

…ge/learn-ql/ql-etudes/river-crossing.rst …ge/learn-ql/beginner/cross-the-river.rstdocs/language/learn-ql/ql-etudes/river-crossing.rst renamed to docs/language/learn-ql/beginner/cross-the-river.rst docs/language/learn-ql/ql-etudes/river-crossing.rst renamed to docs/language/learn-ql/beginner/cross-the-river.rst

@@ -162,5 +162,5 @@ What next?
 ----------
 
 -  Learn more about recursion in the `QL language handbook <https://help.semmle.com/QL/ql-handbook/index.html>`__.
--  Put your QL skills to the test and solve the :doc:`River crossing puzzle <../ql-etudes/river-crossing>`.
+-  Put your QL skills to the test and solve the :doc:`River crossing puzzle <cross-the-river>`.
 -  Start using QL to analyze projects. See :doc:`Learning CodeQL <../../index>` for a summary of the available languages and resources.

docs/language/learn-ql/beginner/crown-the-rightful-heir.rst

@@ -7,8 +7,8 @@ Before starting these tutorials, you can read the :doc:`Introduction to QL <../i
 
 .. toctree::
    :glob:
-   :hidden:
 
    find-the-thief
    catch-the-fire-starter
-   crown-the-rightful-heir
+   crown-the-rightful-heir
+   cross-the-river

docs/language/learn-ql/beginner/ql-tutorials.rst

@@ -34,7 +34,6 @@ If you are new to QL, start by looking at the following topics:
    introduction-to-ql
    about-ql
    beginner/ql-tutorials
-   ql-etudes/river-crossing
 
 CodeQL training and variant analysis examples
 *********************************************