Cleanup docs landing page
Cleanup docs landing page

Our docs our wildly out of date and pretty bad, this is a first step at
beginning to clean them up and make them more useful.

* remove the guidelines section. 2 of them are explicitly wrong (API
  Compatibility and Open Standards), and no one actually uses these
  guidelines during development. Yes we want high availability and fault
  tolerance, but listing these design guidelines here is misleading at
  best.
* Don't explain how this document is built, don't need to explain that
  so prominently
* Update the intro based on Nova's mission statement

Change-Id: Ia564a7cacdac0ddab913464ca1c7f9fefb0ee0b5

alvarolopez/nova,belmiromoreira/nova,varunarya10/nova_test_latest,TwinkleChawla/nova,cloudbase/nova,thomasem/nova,edulramirez/nova,rajalokan/nova,eonpatapon/nova,double12gzh/nova,devendermishrajio/nova_test_latest,CloudServer/nova,eonpatapon/nova,klmitch/nova,devendermishrajio/nova_test_latest,jianghuaw/nova,zhimin711/nova,scripnichenko/nova,CCI-MOC/nova,felixma/nova,belmiromoreira/nova,vmturbo/nova,Juniper/nova,Francis-Liu/animated-broccoli,ruslanloman/nova,adelina-t/nova,cloudbase/nova,apporc/nova,dims/nova,tangfeixiong/nova,alaski/nova,zzicewind/nova,j-carpentier/nova,CloudServer/nova,jianghuaw/nova,zaina/nova,rajalokan/nova,Stavitsky/nova,nikesh-mahalka/nova,double12gzh/nova,JianyuWang/nova,klmitch/nova,sebrandon1/nova,Juniper/nova,iuliat/nova,yosshy/nova,kimjaejoong/nova,whitepages/nova,cernops/nova,zzicewind/nova,BeyondTheClouds/nova,CCI-MOC/nova,mandeepdhami/nova,Juniper/nova,openstack/nova,rajalokan/nova,kimjaejoong/nova,jianghuaw/nova,openstack/nova,tangfeixiong/nova,joker946/nova,vmturbo/nova,barnsnake351/nova,isyippee/nova,tudorvio/nova,NeCTAR-RC/nova,JioCloud/nova_test_latest,MountainWei/nova,watonyweng/nova,vmturbo/nova,mahak/nova,JianyuWang/nova,TwinkleChawla/nova,CEG-FYP-OpenStack/scheduler,raildo/nova,raildo/nova,akash1808/nova,bigswitch/nova,hanlind/nova,openstack/nova,hanlind/nova,sebrandon1/nova,gooddata/openstack-nova,vmturbo/nova,mmnelemane/nova,barnsnake351/nova,thomasem/nova,sebrandon1/nova,mandeepdhami/nova,yatinkumbhare/openstack-nova,JioCloud/nova,iuliat/nova,yatinkumbhare/openstack-nova,rahulunair/nova,zaina/nova,rahulunair/nova,tealover/nova,alaski/nova,scripnichenko/nova,Juniper/nova,edulramirez/nova,LoHChina/nova,Tehsmash/nova,cernops/nova,isyippee/nova,adelina-t/nova,mikalstill/nova,gooddata/openstack-nova,JioCloud/nova_test_latest,jianghuaw/nova,mikalstill/nova,tealover/nova,shail2810/nova,zhimin711/nova,LoHChina/nova,noironetworks/nova,gooddata/openstack-nova,cyx1231st/nova,jeffrey4l/nova,joker946/nova,JioCloud/nova,fnordahl/nova,ruslanloman/nova,rahulunair/nova,ted-gould/nova,klmitch/nova,shail2810/nova,Francis-Liu/animated-broccoli,yosshy/nova,phenoxim/nova,cernops/nova,BeyondTheClouds/nova,rajalokan/nova,apporc/nova,dims/nova,bgxavier/nova,devendermishrajio/nova,akash1808/nova,jeffrey4l/nova,bigswitch/nova,noironetworks/nova,gooddata/openstack-nova,j-carpentier/nova,varunarya10/nova_test_latest,MountainWei/nova,tudorvio/nova,mikalstill/nova,hanlind/nova,takeshineshiro/nova,nikesh-mahalka/nova,mahak/nova,cloudbase/nova,watonyweng/nova,ted-gould/nova,CEG-FYP-OpenStack/scheduler,takeshineshiro/nova,whitepages/nova,phenoxim/nova,BeyondTheClouds/nova,Stavitsky/nova,bgxavier/nova,Tehsmash/nova,klmitch/nova,felixma/nova,cyx1231st/nova,akash1808/nova_test_latest,akash1808/nova_test_latest,devendermishrajio/nova,fnordahl/nova,mmnelemane/nova,NeCTAR-RC/nova,alvarolopez/nova,mahak/nova