Fix redirect (#1791)

Author: Dave Cuthbert

config/redirects

@@ -1571,7 +1571,7 @@ raw: ${prefix}/v2.8/release-notes/2.8-changes -> ${base}/v3.0/release-notes/3.0/
 [v4.2-*]: ${prefix}/${version}/reference/command/getPrevError -> ${base}/${version}/reference/command/
 [v4.2-*]: ${prefix}/${version}/reference/method/db.getPrevError -> ${base}/${version}/reference/method/
 [v4.2-*]: ${prefix}/${version}/reference/read-preference -> ${base}/${version}/core/read-preference/
-[v4.2-*]: ${prefix}/${version}/reference/method/sh.startBalancer -> ${base}/${version}/reference/method/js-sharding/
+[v4.2-*]: ${prefix}/${version}/reference/method/sh.getBalancerHost -> ${base}/${version}/reference/method/js-sharding/
 
 # Redirects for 4.0 or earlier (i.e. before 4.2), stopping at v3.0 since otherwise to help slow the growth in the number of our redirects