x86/msr: Add a pointer to an URL which contains further details

After having collected the majority of reports about MSRs being written
by userspace tools and what tools those are, and all newer reports
mostly repeating, add an URL where detailed information is gathered and
kept up-to-date.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201205002825.19107-1-bp@alien8.de

arch/x86/kernel/msr.c

@@ -99,8 +99,9 @@ static int filter_write(u32 reg)
 	if (!__ratelimit(&fw_rs))
 		return 0;
 
-	pr_warn("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
+	pr_warn("Write to unrecognized MSR 0x%x by %s (pid: %d).\n",
 	        reg, current->comm, current->pid);
+	pr_warn("See https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/about for details.\n");
 
 	return 0;
 }