update readme

Readme.rst

-This is intended as a user-friendly (and easy to customize) alternative to the previous exam statistic script
-written in perl.
+This is intended as a user-friendly (and easy to customize) alternative to the previous exam statistics script.
 
 .. role:: bash(code)
    :language: bash
@@ -8,10 +7,10 @@ written in perl.
 Installation
 ============
 
-Run :bash:`./install.sh`. Be patient, if you run this on a D-MATH computer it will
-take >5min.
+Run :bash:`./install.sh`. This will download and compile the required R-packages and install
+pandas and xlwt for python 3.
 
-Of course you have to clone or download the git repo first:
+You have to clone or download the git repo first:
 
 .. code:: shell
 
@@ -35,11 +34,12 @@ Usage
 3. Open ``marks.xls`` in a spreadsheet editor (for example localc) and enter
    the number of points per task for each student (Columns A1..An). Add or remove
    columns for tasks as needed. Save as Excel document to ``marks.xls``.
-4. Open the file ``statistics.Rnw`` in a text editor and fill the data in the block called "User
-   Settings".
+4. Open the file ``statistics.Rnw`` in a text editor and fill in the variables in the
+   block "User Settings". That means the lecture title, the interpolation points for
+   the grading scale and the maximal number of points per task.
 5. Open a shell and type :bash:`./2-generate-stats-and-edoz-upload`. This will generate the
    files ``statistics.pdf`` and ``edoz-final.txt``
-6. Check the grades of a few students manually to make sure that results in
+6. Check the grades of a few students manually to make sure that the results in
    ``edoz-final.txt`` are correct.
 7. Upload ``edoz-final.txt`` to edoz by clicking on ``Import Data``.
 
@@ -52,7 +52,7 @@ Preview
 
 Links
 =====
-If you'd like to customize the script have a look at the following packages and the file ``statistics.Rnw``.
+If you'd like to customize the script, have a look at the following packages and the file ``statistics.Rnw``.
 
 - Manipulate data in R: `dplyr <https://cran.rstudio.com/web/packages/dplyr/vignettes/introduction.html>`_
 - Plots in R `ggplot2 <http://www.cookbook-r.com/Graphs/>`_