Fix the 'but is not' typo.
fix typo in CONTRIBUTING.md
Merge pull request #2872 from goldmann/runtime_typo

Fix the 'but is not' typo
Merge pull request #2884 from nikai3d/patch-1

fix typo in CONTRIBUTING.md
Add mkseccomp.pl, helper script to make seccomp profiles.
Merge pull request #2887 from kleptog/master

Add mkseccomp.pl, helper script to make seccomp profiles.