"analysis" goes in the "settings" block, which goes either before or after the "mappings" block when creating an index.
"settings": {
"analysis": {
"analyzer": {
"alfeanalyzer": {
"type": "pattern",
"pattern": "\\s+"
}
}
}
},
"mappings": {
"alfedoc": { ... }
}
Here's a good complete, example: Example 1