update installation and help documents

2 jobs for master in 14 minutes and 41 seconds
Name Stage Failure
build Build
reading sources... [ 32%] bob/bob.io.base/doc/py_api
reading sources... [ 32%] bob/bob.io.image/README
reading sources... [ 33%] bob/bob.io.image/doc/cpp_api
reading sources... [ 33%] bob/bob.io.image/doc/guide
/scratch/builds/bob/docs/miniconda/conda-bld/bob.docs_1642565239159/test_tmp/run_test.sh: line 7: 1527 Segmentation fault (core dumped) sphinx-build /scratch/builds/bob/docs/conda/../doc /scratch/builds/bob/docs/conda/../sphinx
Tests failed for bob.docs-2018.02.21b0-h16cf79f_49.conda - moving package to /scratch/builds/bob/docs/miniconda/conda-bld/broken
TESTS FAILED: bob.docs-2018.02.21b0-h16cf79f_49.conda
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1