Removing the requirements.txt from docs building dependencies

Author: petyaslavova

.readthedocs.yml

@@ -3,7 +3,6 @@ version: 2
 python:
   install:
     - requirements: ./docs/requirements.txt
-    - requirements: requirements.txt
 
 build:
   os: ubuntu-20.04

doctests/README.md

@@ -16,9 +16,9 @@ Examples are standalone python scripts, committed to the *doctests* directory. T
 ```requirements.txt``` and ```dev_requirements.txt``` from this repository have been installed, as per below.
 
 ```bash
-pip install -r requirements.txt
 pip install -r dev_requirements.txt
 pip install -r doctests/requirements.txt
+pip install .
 ```
 
 Note - the CI process, runs the basic ```black``` and ```isort``` linters against the examples. Assuming