Add Differential Revision: to svnlite's FreeBSD template

[xmj]

Summary

Add Differential Revision: to svnlite's FreeBSD template.
The Ports Differential Revision for devel/subversion can be found on
https://reviews.freebsd.org/D600

Test Plan

cd src/usr.bin/svn/ && make

[peter]

Is one expected to enter something like: "D763" or "https://reviews.freebsd.org/D763"? I suspect with this text we'll get both interpretations.

[mat]

In D763#4, @peter wrote:

Is one expected to enter something like: "D763" or "https://reviews.freebsd.org/D763"? I suspect with this text we'll get both interpretations.

The full URL is needed, the comment should say so, yes. I now see the ports version doesn't say so either. Something like:

+ svn_stringbuf_appendcstr(default_msg, "> Differential Revision: https://reviews.freebsd.org/D### (full review URL is needed)." APR_EOL_STR);