Update docstring

Author: kmorkos

src/db_options.rs

@@ -5068,10 +5068,18 @@ impl CompactOptions {
         }
     }
 
-    /// If set to < 0 or > 1, RocksDB leaves blob_garbage_collection_age_cutoff
-    /// from ColumnFamilyOptions in effect. Otherwise, it will override the
-    /// user-provided setting. This enables customers to selectively override the
-    /// age cutoff.
+    /// Override `CompactRangeOptions::blob_garbage_collection_age_cutoff` for a
+    /// single manual compaction.
+    ///
+    /// If set to `< 0` or `> 1`, RocksDB leaves the
+    /// `blob_garbage_collection_age_cutoff` from `ColumnFamilyOptions` in
+    /// effect (this is the default, `-1`). Otherwise, it overrides the
+    /// user-provided setting for the duration of this compaction. This
+    /// enables callers to selectively override the age cutoff per
+    /// `compact_range` call.
+    ///
+    /// See [`Options::set_blob_gc_age_cutoff`] for the CF-level setter that
+    /// this value overrides.
     pub fn set_blob_garbage_collection_age_cutoff(&mut self, v: c_double) {
         unsafe {
             ffi::rocksdb_compactoptions_set_blob_garbage_collection_age_cutoff(self.inner, v);