[compression] improve/fix docs

docs/source/notebooks/DataCompression.ipynb

@@ -414,6 +414,30 @@
     "decode(obj.values)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "89deabde",
+   "metadata": {},
+   "source": [
+    "Waveform compression settings can also be specified at the LGDO level by attaching a `compression` attribute to the `values` attribute of a `WaveformTable` object:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "24e8f49f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from lgdo.compression import ULEB128ZigZagDiff\n",
+    "\n",
+    "wfs.values.attrs[\"compression\"] = ULEB128ZigZagDiff()\n",
+    "store.write_object(wfs, \"waveforms\", \"data.lh5\", wo_mode=\"of\")\n",
+    "\n",
+    "obj, _ = store.read_object(\"waveforms\", \"data.lh5\", decompress=False)\n",
+    "obj.values.attrs[\"codec\"]"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "3999f30d",

src/lgdo/lh5_store.py

@@ -796,9 +796,10 @@ def write_object(
           passed directly to :meth:`h5py.Group.create_dataset`.
 
         :class:`.WaveformCodec` object
-          If `obj` is a :class:`.WaveformTable`, compress its `values` using
-          this algorithm. More documentation about the supported waveform
-          compression algorithms at :mod:`.lgdo.compression`.
+          If `obj` is a :class:`.WaveformTable` and ``obj.values`` holds the
+          attribute, compress ``values`` using this algorithm. More
+          documentation about the supported waveform compression algorithms at
+          :mod:`.lgdo.compression`.
 
         If the `obj` :class:`.LGDO` has a `hdf5_settings` attribute holding a
         dictionary, it is interpreted as a list of keyword arguments to be