Installation Requirements Information for Windows

[ajuanjojjj]

It'd be nice to add somewhere that fbclient.dll and gds32.dll need to be added to the windows PATH for the library to work

I (now) know this noted on https://www.php.net/manual/en/ibase.installation.php, but I think the repo is sufficiently separated from said docs for this to be able to be missed, and given that the shown error if this is not done is the incredibly misleading "The specified module could not be found", a simple note on the Releases section will probably save many hours to anyone unlucky enough to miss it.