make Section::Version accept many format strings

This changeset allows a `Pod::Weaver::Section::Version` format to be specified over multiple lines in a `weaver.ini` configuration file.  Each format is rendered as its own line of POD, allowing things like this in a `weaver.ini` file to work as expected:

```
[Version]
format = version %v
format =
format = This module's version numbers follow the conventions described at
format = L<semver.org|http://semver.org/>.
```

```
VERSION
       version 1.012078
       
       This module's version numbers follow the conventions described at
       semver.org <http://semver.org/>.
```