reviewed installation section of online documentation; minor corrections

Documentation/doctrees/Documentation/Api/api_python.doctree

Documentation/doctrees/Documentation/Input/control.doctree

...ation/doctrees/Documentation/Input/control_params.doctree

Documentation/doctrees/Documentation/Input/ecmwf_env.doctree

Documentation/doctrees/Documentation/Input/run.doctree

Documentation/doctrees/Installation/gateway.doctree

Documentation/doctrees/Installation/local.doctree

Documentation/doctrees/Installation/remote.doctree

Documentation/doctrees/environment.pickle

Documentation/doctrees/index.doctree

Documentation/doctrees/installation.doctree

Documentation/doctrees/quick_start.doctree

Documentation/html/.buildinfo

Documentation/html/.nojekyll

Documentation/html/Documentation/Api/api_python.html

Documentation/html/Documentation/Input/control.html

Documentation/html/Documentation/Input/control_params.html

Documentation/html/Documentation/Input/ecmwf_env.html

Documentation/html/Documentation/Input/fortran_makefile.html

Documentation/html/Documentation/Input/run.html