Fix \param tags in mcr_howard and put_property

[karpovantonme]

Two Doxygen comments where the tags do not line up with the code. Documentation only, no code touched.

mcr_howard, howard_cycle_ratio.hpp

Two separate problems in one comment.

Three \param tags are written mid-line, after the text of the previous parameter:

 * \param vim  Vertex Index Map. Read property Map: V -> [0,
 * num_vertices(g)). \param ewm  edge weight map. Read property map: E
 * -> R \param ew2m  edge weight map. Read property map: E -> R+ \param
 * infty A big enough value ...

Doxygen only recognises a command at the start of a line, so ewm and ew2m are currently read as prose belonging to vim, and the two parameters come out undocumented. Looks like a reflow that ran over the tags at some point.

The other half: infty and cmp are documented, but the constructor does not take them. It takes (g, vim, ewm, ew2m), and grep finds no other mcr_howard( in the file. m_cmp exists as a member and is default-constructed, so the comment may date from a version that took a comparator; infty does not appear anywhere in the file outside this comment.

I removed those two and put each remaining tag on its own line.

put_property, visitors.hpp

 * @param tag Event Filter
...
inline property_put< PropertyMap, EventTag > put_property(
    PropertyMap property_map,
    typename property_traits< PropertyMap >::value_type value, EventTag)

The third argument has no name, and Doxygen cannot attach a @param to an unnamed parameter. Naming it would document the tag but goes against what the rest of the file does (every EventTag argument in visitors.hpp is unnamed), so I moved the explanation into the description instead and left the signature alone.

Both are what clang -Wdocumentation reports as parameter '...' not found in the function declaration.

I can split this into two pull requests if you would rather review them separately.

[jeremy-murphy]

Thank you!