readme: refer to impish kernel

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

README

@@ -8,10 +8,6 @@ We currently use the Ubuntu kernel sources, available from:
 Ubuntu will maintain those kernels till:
 
  https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
- or
- https://pve.proxmox.com/pve-docs/chapter-pve-faq.html#faq-support-table
-
- whatever happens to be earlier.
 
 
 Additional/Updated Modules:
@@ -64,7 +60,7 @@ pve-kernel-meta
 ---------------
 
 depends on latest kernel and header package within a certain kernel series,
-e.g., pve-kernel-5.11 / pve-headers-5.11
+e.g., pve-kernel-4.15 / pve-headers-4.15
 
 git clone git://git.proxmox.com/git/pve-kernel-meta.git
 
@@ -142,34 +138,45 @@ NOTE: For the exact and current list see debian/rules (PVE_CONFIG_OPTS)
 	 CONFIG_BLK_DEV_RBD=m
 
 - enable IBM JFS file system as module
-  requested by users (bug #64)
+
+  enable it as requested by users (bug #64)
 
 - enable apple HFS and HFSPLUS as module
-  requested by users
+
+  enable it as requested by users
 
 - enable CONFIG_BCACHE=m (requested by user)
 
 - enable CONFIG_BRIDGE=y
-  to avoid warnings on boot, e.g. that net.bridge.bridge-nf-call-iptables is an unknown key
+
+  Else we get warnings on boot, that
+  net.bridge.bridge-nf-call-iptables is an unknown key
 
 - enable CONFIG_DEFAULT_SECURITY_APPARMOR
+
   We need this for lxc
 
 - set CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
+
   because if not set, it can give some dynamic memory or cpu frequencies 
   change, and vms can crash (mainly windows guest).
+
   see http://forum.proxmox.com/threads/18238-Windows-7-x64-VMs-crashing-randomly-during-process-termination?p=93273#post93273
 
 - use 'deadline' as default scheduler
-  This is the suggested setting for KVM. We also measure bad fsync performance with ext4 and cfq.
+
+  This is the suggested setting for KVM. We also measure bad fsync
+  performance with ext4 and cfq.
 
 - disable CONFIG_INPUT_EVBUG
-  Module evbug is not blacklisted on debian, so we simply disable it to avoid
-  key-event logs (which is a big security problem)
+
+  Module evbug is not blacklisted on debian, so we simply disable it
+  to avoid key-event logs (which is a big security problem)
 
 - enable CONFIG_MODVERSIONS (needed for ABI tracking)
 
 - switch default UNWINDER to FRAME_POINTER
+
   the recently introduced ORC_UNWINDER is not 100% stable yet, especially in combination with ZFS
 
 - enable CONFIG_PAGE_TABLE_ISOLATION (Meltdown mitigation)