building instructions not complete

[GliderGeek]

running the command pip install -r requirements.txt does not work on a standard ubuntu delivery.
additional package installation are necessary, naimly:

• sudo apt-get install libcurl4-gnutls-dev (for xcsoar package)
• sudo apt-get install libxml2-dev (for lxml)
• sudo apt-get install libxslt1-dev (for lxml)

After these are succesfully installed, the pip command works

[GliderGeek]

The building procedure is also lacking something else as the site is not working after building and starting the development server.
after finishing steps 1-3 and changing the static_folder parameter, the following error message is showed:

After clicking ok, some parts of the site become visible, but without functionality: