[AD] /docs MSVC7 specific makefile target

[AJ <aj@xxxxxxxxxx>]

there is a makefile target definition for MSVC7 compiler
it needs to be documented.

i am not familiar with how the documentation gets generated but here is 
what needs to appear in the  /doc/html/allegro045.html

<li>COMPILER_MSVC7=1
<br>Selects MSVC7 specific optimisations.


just under the UNIXTOOLs one would be a good place.
can someone add this please.

aj.