Fix spelling mistakes (#835)

Fix a couple of spelling mistakes in the changelog.

Author: peterguy

docs/technical-changelog.mdx

@@ -187,10 +187,7 @@ This page documents all notable changes to Sourcegraph. For more detailed change
 - (new web ui) Copy URL to clipboard when clicking 'Permalink' [#1774](https://github.com/sourcegraph/sourcegraph/pull/1774)
 - (new web ui) Show file/folder name in title instead of full path [#1735](https://github.com/sourcegraph/sourcegraph/pull/1735)
 - (new web ui) Add survey toast [#1453](https://github.com/sourcegraph/sourcegraph/pull/1453)
-
-#### Serach
-
-- (new web ui) Show loading indictor when navigating up the file tree [#1465](https://github.com/sourcegraph/sourcegraph/pull/1465)
+- (new web ui) Show loading indicator when navigating up the file tree [#1465](https://github.com/sourcegraph/sourcegraph/pull/1465)
 
 #### Sg