[DDOC] Usage of WEB macro for License everywhere

Half of Phobos had `$(WEB)`, the other where still using` <a href=...`
Yes: currect code, generated with this macros:
```
<a href="http://www._zlib.net"><a name="zlib"></a><span class="ddoc_psymbol">zlib</span> library</a>
```
`www._zlib.net` is incorrect reference.