Remove generic boost parm documentation

Author: jrodewig

docs/reference/query-dsl/prefix-query.asciidoc

@@ -16,7 +16,6 @@ GET /_search
         "prefix": {
             "user": {
                 "value": "ki",
-                "boost": 1.0,
                 "rewrite": "constant_score"
             }
         }
@@ -35,18 +34,6 @@ Field you wish to search.
 `value`::
 Beginning characters of terms you wish to find in the provided `<field>`.
 
-`boost`::
-Floating point number used to decrease or increase the
-<<query-filter-context, relevance scores>> of a query. Default is `1.0`.
-Optional.
-+
-You can use the `boost` parameter to adjust relevance scores for searches
-containing two or more queries.
-+
-Boost values are relative to the default value of `1.0`. A boost value between
-`0` and `1.0` decreases the relevance score. A value greater than `1.0`
-increases the relevance score.
-
 `rewrite` (Expert)::
 Method used to rewrite the query. For valid values and more information, see the
 <<query-dsl-multi-term-rewrite, `rewrite` parameter>>. Optional.