Update release(7) to note OSRELEASE is only relevant when the

'install' target is invoked.

While here, bump the sample output version name, and explicitly
add the 'obj' target to avoid polluting the src checkout.

Submitted by:	Trond Endrestol
PR:		243287 (related)
MFC after:	3 days
Sponsored by:	Rubicon Communications, LLC (netgate.com)

share/man/man7/release.7

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 28, 2018
+.Dd January 16, 2020
 .Dt RELEASE 7
 .Os
 .Sh NAME
@@ -570,8 +570,10 @@ target invoked by
 Optional variables:
 .Bl -tag -width ".Ev TARGET_ARCH"
 .It Ev OSRELEASE
-Optional base name for generated media images
-.Pq e.g., FreeBSD-9.0-RC2-amd64 .
+Optional base name for generated media images when invoking the
+.Cm install
+target
+.Pq e.g., FreeBSD-12.1-RELEASE-amd64 .
 Defaults to the output of
 .Ic `uname -s`-`uname -r`-`uname -p`
 within the chroot.
@@ -659,6 +661,7 @@ svn co svn://svn.freebsd.org/base/head src
 cd src
 make buildworld buildkernel
 cd release
+make obj
 make release
 make install DESTDIR=/var/freebsd-snapshot
 .Ed