Improved script generating the .lintr file, fixes #268

[Guillawme]

There is no change to the package code, I simply edited README.md to propose a better script for automatically generating a .lintr file.

With this script, the generated .lintr file will not cause the problem described in #268.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@1f2cb45). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff            @@
##             master    #344   +/-   ##
========================================
  Coverage          ?   85.6%           
========================================
  Files             ?      41           
  Lines             ?    2132           
  Branches          ?       0           
========================================
  Hits              ?    1825           
  Misses            ?     307           
  Partials          ?       0

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1f2cb45...285528e. Read the comment docs.

[jimhester]

Great work, this package is now better thanks to you!