Update relative path for doc-requirements.txt

Author: shriyakalakata

doc/install/dependencies.rst

@@ -392,7 +392,7 @@ The additional Python packages required to build the
 
 The content of :file:`doc-requirements.txt` is also shown below:
 
-.. include:: ../../../requirements/doc/doc-requirements.txt
+.. include:: ../../requirements/doc/doc-requirements.txt
    :literal: