Update README.md
fixed typos from #862 and #868
Fix a typo in the guide
Merge pull request #872 from mquandalle/patch-1

Fix a typo in the guide
Merge pull request #870 from willemx/devel

fixed typos from #862 and #868
Merge pull request #865 from rambo-panda/patch-1

Update README.md
Merge branch 'devel'