Fix watch overload types (#1159)

Author: Ovoda

src/content/docs/useform/watch.mdx

@@ -12,8 +12,8 @@ This method will watch specified inputs and return their values. It is useful to
 
 This function mainly serves **two purposes**:
 
-- <TypeText>`watch(name: string, defaultValue?): unknown`</TypeText>
-- <TypeText>`watch(names: string[], defaultValue?): {[key:string]: unknown}`</TypeText>
+- <TypeText>`watch(name: string, defaultValue?: unknown): unknown`</TypeText>
+- <TypeText>`watch(names: string[], defaultValue?: {[key:string]: unknown}): unknown[]`</TypeText>
 - <TypeText>`watch(): {[key:string]: unknown}`</TypeText>
 
 The explanation of each of these four overloads follows below.