chore: fix a typo in ExtensionType::supports_data_type docs (#7682)

# Which issue does this PR close?

None

# Rationale for this change

Noticed a typo.

# What changes are included in this PR?

Fixes the typo.

# Are there any user-facing changes?

Updated docs.

Author: mbrobbel

arrow-schema/src/extension/mod.rs

@@ -247,7 +247,7 @@ pub trait ExtensionType: Sized {
     /// - deserialization of metadata fails
     fn deserialize_metadata(metadata: Option<&str>) -> Result<Self::Metadata, ArrowError>;
 
-    /// Returns `OK())` iff the given data type is supported by this extension
+    /// Returns `Ok(())` iff the given data type is supported by this extension
     /// type.
     fn supports_data_type(&self, data_type: &DataType) -> Result<(), ArrowError>;