Move docs requirements to docs root folder

docs/source/requirements.txt

@@ -1,6 +0,0 @@
-sphinx-book-theme
-sphinx>=5.0
-sphinx-favicon
-sphinx-design
-pygments>=2.7
-docutils>=0.17.1

docs/source/tech_source.rst

@@ -138,7 +138,7 @@ packages from PyPi:
 
 .. code-block:: bash
 
-   pip install -r docs/source/requirements.txt
+   pip install -r docs/requirements.txt
 
 The documentation can then be built from the root folder in the source code by running: