DOC: fix some doc issues

Some issues in the documentation were identified.

Firstly, some builders names (features map and OBIA) in example configuration files were not consistent with the changes introduced in !120 (merged). Secondly, the auto-generated steps description for the classification tutorial were missing. This is because, since d78ff88c, a check is performed on the input reference shapefile, but no actual shapefile is used. The file containing these steps is manually restored for now, but a long-term solution needs to be developed.