Fix a typo in Clang tool refactoring docs

runtime => run time

Change-Id: I9fcc4b0c8b6156676985428b9eec7a6f3cb3fd34
Reviewed-on: https://chromium-review.googlesource.com/508120
Commit-Queue: danakj <[email protected]>
Reviewed-by: danakj <[email protected]>
Cr-Commit-Position: refs/heads/master@{#472803}
diff --git a/docs/clang_tool_refactoring.md b/docs/clang_tool_refactoring.md
index 2911a1ab..4554646 100644
--- a/docs/clang_tool_refactoring.md
+++ b/docs/clang_tool_refactoring.md
@@ -87,7 +87,7 @@
 to automatically apply the generated replacements and save the results, it
 doesn't work well for Chromium:
 
-*   Clang tools run actions serially, so runtime scales poorly to tens of
+*   Clang tools run actions serially, so run time scales poorly to tens of
     thousands of files.
 *   A parsing error in any file (quite common in NaCl source) prevents any of
     the generated replacements from being applied.