[MINOR] fix typo & remove unused import (#929)

rising-star92 · rising-star92 · commit 63bfe0e16a76 · 2019-10-15T19:45:28.000+02:00
![스크린샷 2019-10-15 오후 10 19 46](https://user-images.githubusercontent.com/44108233/66835112-ea36b780-ef99-11e9-96ed-25e1d6f98552.png)
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -1,4 +1,4 @@
 # Contributing Guide
 
-Moved to [the offical documentation](https://koalas.readthedocs.io/en/latest/development/contributing.html).
+Moved to [the official documentation](https://koalas.readthedocs.io/en/latest/development/contributing.html).
 
diff --git a/databricks/koalas/indexing.py b/databricks/koalas/indexing.py
@@ -28,7 +28,6 @@
 
 from databricks.koalas.internal import _InternalFrame
 from databricks.koalas.exceptions import SparkPandasIndexingError, SparkPandasNotImplementedError
-from databricks.koalas.utils import column_index_level
 
 
 def _make_col(c):

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`	`1`	`# Contributing Guide`
`2`	`2`
`3`		`-Moved to [the offical documentation](https://koalas.readthedocs.io/en/latest/development/contributing.html).`
	`3`	`+Moved to [the official documentation](https://koalas.readthedocs.io/en/latest/development/contributing.html).`
`4`	`4`