Update mailing list address.

And while here, improve the text a bit too.

Author: anttikantee

README.md

@@ -1,19 +1,22 @@
+_Note: Unless you are a developer integrating rump kernels into
+your project, there should be no reason to be here._
+
 This repository contains a git mirror of NetBSD source code relevant to
-rump kernels.  There are three basic branches (note, these branches
-have no overlap):
+rump kernels.  There are three basic, non-overlapping branches:
 
-* kernel-src: NetBSD sources necessary for building rump kernel components
-* user-src: selection of NetBSD userspace sources for appstacks on top of rump kernel (libs, utils)
-* posix-src: NetBSD sources for rump kernels on POSIX-y platforms
+* kernel-src: rump kernel components and build tools
+* user-src: selection of NetBSD userspace sources for providing a POSIX-y interface _on top_ of a rump kernel
+* posix-src: support for running rump kernels _on_ POSIX-y platforms
 
-For convenience, we provide "consumer-ready" merged branches:
+For most projects, any of the above branches are not useful alone,
+so we provide merged versions:
 
 * buildrump-src: kernel+posix, what buildrump.sh wants in POSIX mode
-* appstack-src: kernel+user, what you want for most appstacks (e.g. Xen)
+* appstack-src: kernel+user, useful for e.g. unikernels
 * all-src: kernel+user+posix
 
-Note, the goal of this repository is to mirror NetBSD sources, so
-pullup requests will not be accepted.  Either submit patches directly
-to NetBSD via the [problem report web
+Note, this repository is a mirror of NetBSD sources, so patches will
+not be accepted.  Either submit patches directly to NetBSD via the
+[problem report web
 page](http://netbsd.org/cgi-bin/sendpr.cgi?gndb=netbsd) or to the
-[rumpkernel-users mailing list](https://lists.sourceforge.net/lists/listinfo/rumpkernel-users).
+[rumpkernel-users mailing list](https://www.freelists.org/list/rumpkernel-users).