Convert funky space-like characters to space

Apparently the original HTML (or something in the conversion process)
gave us some funky UTF-8 character, (0xC2 0xA0), where I would expect
a simple space. This was causing problems when trying to cut-and-paste
example commands from the document, (since bash wouldn't break the
command-line on the non-space characters). Replace all these with good
old ASCII spaces.