Doc: update change log for 1.1.18-rc2

ChangeLog

@@ -1,3 +1,19 @@
+* Mon Oct 16 2017 Ken Gaillot <kgaillot@redhat.com> Pacemaker-1.1.18-rc2
+- Update source tarball to revision: 62e8d4b
+- Changesets: 31
+- Diff:       23 files changed, 484 insertions(+), 284 deletions(-)
+
+- Features added since Pacemaker-1.1.18-rc1
+
+- Changes since Pacemaker-1.1.18-rc1
+  + fix regressions introduced in rc1 (don't break crm_resource --lifetime,
+    avoid memory leak when caching meta-data,
+    keep previous format of crm_mon XML output for bundles)
+  + crm_mon: avoid infinite process spawning if -E script can't be run
+  + crm_mon: don't show previous exit-reason for failed action with none
+  + libcrmservice: list systemd unit files, not only active units (BZ#5299)
+  + libcrmservice: parse long description correctly for LSB meta-data
+
 * Fri Oct 06 2017 Ken Gaillot <kgaillot@redhat.com> Pacemaker-1.1.18-rc1
 - Update source tarball to revision: cb21fde
 - Changesets: 428