doc: use reST note directive
The 'NOTE: bla bla' syntax was for asciidoc and is still present in a
couple of docstrings. The docstrings will be converted to reST format
when minirst knows how to handle it.
% file replaced with directory
adding a
% should fail - would corrupt dirstate
abort: file 'a' in dirstate clashes with 'a/a'
% directory replaced with file
adding a/a
% should fail - would corrupt dirstate
abort: directory 'a' already in dirstate
% directory replaced with file
adding b/c/d
% should fail - would corrupt dirstate
abort: directory 'b' already in dirstate