Remove documentation generation instr. from README.

Author: Vasileios Karakasis

README.md

@@ -15,29 +15,3 @@ Users can create their own test hierarchies, create test factories for generatin
 ## Documentation
 
 The official documentation is maintained [here](https://eth-cscs.github.io/reframe/index.html).
-
-### Manually generate the documentation
-
-In order to generate the documentation yourself, these are the necessary steps:
-
-1. Install [pandoc](https://pandoc.org).
-2. Install the Python requirements (you can do that from within a virtual environment):
-   ```
-   pip install -r docs/requirements.txt
-   ```
-
-Generate the documentation:
-```
-make -C docs
-```
-
-And view it by opening `docs/html/index.html`.
-
-If you want to view also the old documentation, you should first do the following:
-
-```
-cd docs/html
-python -m http.server # or python -m SimpleHTTPServer for Python 2
-```
-
-You can can now view all the documentation (new and old) by opening `localhost:8000` in your browser.