Fix broken link from README.md

']' was appended accidentally.

Bug: None
Change-Id: I5e07be3848a4b8b2483f8e2a7e61126ae8eeefb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368696
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800621}

third_party/blink/renderer/core/paint/README.md

@@ -727,7 +727,7 @@ display items directly.
 
 ### PaintNG
 
-[LayoutNG](../layout/ng/README.md]) is a project that will change how Layout
+[LayoutNG](../layout/ng/README.md) is a project that will change how Layout
 generates geometry/style information for painting. Instead of modifying
 LayoutObjects, LayoutNG will generate an NGFragment tree.