Four corrections in file

line 413 : against the :kbd:`multipolygon` layer, ----> `multipolygon` should be `multipolygons`

line 428 : to use again the :kbd:`multipolygon` data  ----> `multipolygon` should be `multipolygons`

line 471 : smoother. Compare this: ----->  double space before 'Compare'

line 850 ; The schema for the table (enter :kbd:`\\d people`) looks like this:: --> '\d people' need to be '\\d' to show the backslash
Merge pull request #413 from DiGro/patch-1

Four corrections in file