Fixing typo in toctree formatting

Author: datapythonista

doc/source/user_guide/index.rst

@@ -6,24 +6,24 @@
 User Guide
 ==========
 
-..toctree::
-   :maxdepth: 2
+.. toctree::
+    :maxdepth: 2
 
-   io
-   indexing
-   advanced
-   merging
-   reshaping
-   text
-   missing_data
-   categorical
-   visualization
-   computation
-   groupby
-   timeseries
-   timedeltas
-   style
-   options
-   enhancingperf
-   sparse
-   gotchas
+    io
+    indexing
+    advanced
+    merging
+    reshaping
+    text
+    missing_data
+    categorical
+    visualization
+    computation
+    groupby
+    timeseries
+    timedeltas
+    style
+    options
+    enhancingperf
+    sparse
+    gotchas