Don't use dashes in table fields of .md files

It makes gitiles sad.

Change-Id: I54c1c326bbc579e5591ad5cffae06650d5f24957
Reviewed-on: https://chromium-review.googlesource.com/311082
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>
diff --git a/README.md b/README.md
index 8815196..d2c28c5 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 |                |  Direct3D 9   |    Direct3D 11      |    Desktop GL      |    GL ES  |
 |----------------|:-------------:|:-------------------:|:------------------:|:---------:|
 | OpenGL ES 2.0  |    complete   |      complete       |     complete       |   planned |
-| OpenGL ES 3.0  |     -----     |  nearing completion | nearing completion |   planned |
+| OpenGL ES 3.0  |               |  nearing completion | nearing completion |   planned |
 [Level of OpenGL ES support via backing renderers]
 
 |             |    Direct3D 9  |   Direct3D 11  |   Desktop GL  |