DOCS-16154 Fixes typo in Server Parameters (#3203)

* DOCS-16154 Fixes typo in Server Parameters

* Fixes build issue

Author: kennethdyer

source/reference/parameters.txt

@@ -3224,7 +3224,7 @@ Sharding Parameters
 
    *Default*: 1
 
-   |both|
+   |mongod-only|
 
    Specifies an integer that sets the number of threads on the source
    shard and the receiving shard for :ref:`chunk migration