Fix id attribute on h3 tag for 4.2.x and earlier instructions

The id attribute on the h3 tag for the 4.2.x and earlier instructions was
branch-40x-.... which was the same as for the 4.0.x and earlier instructions.
This patch corrects the tag to be branch-42x-...

Change-Id: I3f498820ed743cafae9dd8a03f14877db48aadfb
1 file changed