Revert "Add instructions to fix path on OS X El Capitan"

For years, OS X has mistakently invoked `path_helper` in `/etc/zshenv`
(affecting all zsh runtimes, even non-interactive shells such as
scripts) instead of from `/etc/zprofile` where it should have been
because it needs to only run once for a login shell.

This frustrated a lot of users since `path_helper` would unexpectedly
reorder their PATH by putting system paths first during nested
invocations of zsh. Many have disabled their `path_helper` because they
believed it to be the culprit. Instead, what they should have done is
fixed the OS X configuration bug and renamed their `/etc/zshenv` to
`/etc/zprofile`.

Recently, El Capitan shipped and users of zsh rejoiced because it has
finally fixed its faulty zsh configuration: the `path_helper` is now
correctly invoked from `/etc/zprofile`. This was a deliberate change on
Apple's part and is a BUG FIX, NOT A REGRESSION.

However, now this project suggests the opposite: revert the El Capitan
fix and move `/etc/zprofile` to `/etc/zshenv`. This is unwise since it
teleports us to the olden days of broken zsh configuration. Please don't
instruct users to break their system.

This reverts commit 15de0bcfee.

README.md

@@ -45,18 +45,6 @@ You can safely run `rcup` multiple times to update:
 You should run `rcup` after pulling a new version of the repository to symlink
 any new files in the repository.
 
-#### Note for OS X El Capitan Users
-
-OS X El Capitan (10.11) calls `path_helper` from `/etc/zprofile`, which gets
-sourced *after* `.zshenv`, and will reorder your path in such a way that
-installed software such as Ruby, rbenv, Homebrew, etc. may not work correctly.
-You can rename the file to prevent it from editing your environment path after
-changes made in `.zshenv`:
-
-```shell
-% sudo mv /etc/{zprofile,zshenv}
-```
-
 Make your own customizations
 ----------------------------