[DOCS] Fix typo in mapping date format docs
[DOCS] Fix typo in mapping date format docs

scorpionvicky/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,nknize/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch