doc/install_and_upgrade.md: update OS X

doc/install_and_upgrade.md

@@ -67,36 +67,29 @@ Yosemite and Mavericks as well, and may also work on older versions (YMMV).
 
 ### Using Homebrew
 
-**Warning:** the Homebrew version of stack-1.1.2 has some
-[problems](https://github.com/commercialhaskell/stack/issues/2182) not present
-in the official binary distribution used in the manual download.  As such, we
-do not currently recommend installing Stack using Homebrew.
-
 If you have a popular [brew](http://brew.sh/) tool installed, you can just do:
 
-```
-brew install haskell-stack
-```
+    brew install haskell-stack
 
-* The Homebrew formula and bottles lag slightly behind new Stack releases,
+* The Homebrew formula and bottles are **unofficial** and lag slightly behind new Stack releases,
 but tend to be updated within a day or two.
-* At later stage, running `stack setup` might fail with `configure: error: cannot run C compiled programs.` in which case you should run `xcode-select --install`.
 * Normally, Homebrew will install from a pre-built binary (aka "pour from a
 bottle"), but if `brew` starts trying to build everything from source (which
 will take hours), see
 [their FAQ on the topic](https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/FAQ.md#why-do-you-compile-everything).
 
+### Notes
 
+After installation, running `stack setup` might fail with `configure: error: cannot run C compiled programs.` in which case you should run:
 
-### Notes
+    xcode-select --install
 
 If you are on OS X 10.11 ("El Capitan") and encounter either of these
 problems, see the linked FAQ entries:
 
   * [GHC 7.8.4 fails with `/usr/bin/ar: permission denied`](faq.md#usr-bin-ar-permission-denied)
   * [DYLD_LIBRARY_PATH is ignored](faq.md#dyld-library-path-ignored)
 
-
 ## Ubuntu
 
 *note*: for 32-bit, use the [generic Linux option](#linux)