Add example, fix type

src/db_options.rs

@@ -414,12 +414,24 @@ impl Options {
         }
     }
 
+    /// Sets the optimize_filters_for_hits flag
+    ///
+    /// Default: `false`
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use rocksdb::Options;
+    ///
+    /// let mut opts = Options::default();
+    /// opts.set_optimize_filters_for_hits(true);
+    /// ```
     pub fn set_optimize_filters_for_hits(&mut self, optimize_for_hits: bool) {
         unsafe {
-            ffi::rocksdb_options_set_optimize_filters_for_hits(self.inner, optimize_for_hits as c_uchar);
+            ffi::rocksdb_options_set_optimize_filters_for_hits(self.inner, optimize_for_hits as c_int);
         }
     }
-    
+
     /// Sets the number of open files that can be used by the DB. You may need to
     /// increase this if your database has a large working set. Value `-1` means
     /// files opened are always kept open. You can estimate number of files based