Bring back disabling-default-password docs section
Bring back disabling-default-password docs section

There are multiple references to this section in different areas of the
documentation. This commit brings back this section to fix the build.

A more extensive PR updating the documentation for "no default
password" work will follow up.

Original commit: elastic/x-pack-elasticsearch@0378e78c8af9d5a31081ac93f8eb21c8b838c601

scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,strapdata/elassandra,robin13/elasticsearch,gingerwizard/elasticsearch,strapdata/elassandra,vroyer/elassandra,gfyoung/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,strapdata/elassandra,gingerwizard/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,vroyer/elassandra,coding0011/elasticsearch,gfyoung/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,nknize/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,vroyer/elassandra,strapdata/elassandra,GlenRSmith/elasticsearch,HonzaKral/elasticsearch,uschindler/elasticsearch,strapdata/elassandra