Merge pull request #427 from lgvaz/mkdir

adds mkdir

Author: jph00

fastcore/_modidx.py

@@ -450,6 +450,7 @@
                                 'fastcore.xtras.local2utc': 'https://fastcore.fast.ai/xtras.html#local2utc',
                                 'fastcore.xtras.mapped': 'https://fastcore.fast.ai/xtras.html#mapped',
                                 'fastcore.xtras.maybe_open': 'https://fastcore.fast.ai/xtras.html#maybe_open',
+                                'fastcore.xtras.mkdir': 'https://fastcore.fast.ai/xtras.html#mkdir',
                                 'fastcore.xtras.modified_env': 'https://fastcore.fast.ai/xtras.html#modified_env',
                                 'fastcore.xtras.modify_exception': 'https://fastcore.fast.ai/xtras.html#modify_exception',
                                 'fastcore.xtras.obj2dict': 'https://fastcore.fast.ai/xtras.html#obj2dict',