WSIT documentation should refer to Metro where appropriate

At least the documentation in the WSIT CVS (wsit/docs/howto) is talking about
WSIT exclusively. In many instances, the references to WSIT should be replaced
by Metro. The same goes probably for wsit/samples.

Note that the installation files for Metro 1.2 have already been renamed, e.g.
jax-ws-latest-wsit.zip is now metro.zip.
#### Environment
Operating System: All
Platform: Macintosh
#### Affected Versions
[1.2]

Source: [https://github.com/javaee/metro-wsit/issues/817](https://github.com/javaee/metro-wsit/issues/817)
Author: glassfishrobot

Start in wsit/docs/howto and then inspect wsit/samples for references that still use WSIT exclusively. Compare the documentation with the Metro 1.2 installation names, including metro.zip, and update references where Metro is the appropriate product name. Done means the affected documentation no longer uses outdated WSIT naming in those areas.

Written by the indexing model from the issue text.