Fix upgrade to compatibility matrix

Author: jyemin

docs/reference/content/upgrading.md

@@ -97,7 +97,7 @@ The following table specifies the compatibility of the MongoDB Java driver for u
 
 |Java Driver Version|MongoDB 2.6|MongoDB 3.0 |MongoDB 3.2|MongoDB 3.4|MongoDB 3.6|MongoDB 4.0|MongoDB 4.2|
 |-------------------|-----------|------------|-----------|-----------|-----------|-----------|-----------|
-    |Version 3.12       |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |
+|Version 3.12       |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |
 |Version 3.11       |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |
 |Version 3.10       |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |     |
 |Version 3.9        |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |  ✓  |     |