misc/xcode: fix typos

R=golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/5756043

misc/xcode/3/README

 This directory contains files for Go syntax highlighting in Xcode 3.x.
-See the comments go.pbfilespec and go.xclangspec for installation
+See the comments in go.pbfilespec and go.xclangspec for installation
 instructions.

misc/xcode/4/README

 This directory contains files for Go syntax highlighting in Xcode 4.x.
-For installation; read, edit and run go4xcode.sh
+For installation, read, edit, and run go4xcode.sh .
\ No newline at end of file