[PATCH] Update LangRef now that a DataLayout is mandatory.

[Mehdi AMINI]

================
Comment at: docs/LangRef.rst:1531
@@ +1530,3 @@
+that does not embed this target-specific detail into the IR. If you
+don't specify the string, the default specifications will be used to
+generate a Data Layout and the optimizations phases will operate
----------------
echristo wrote:
> Can you specify what you mean by specifications here?
I reused the vocabulary of the previous paragraphs in this section:

    target datalayout = "layout specification"

The *layout specification* consists of a list of specifications
separated by the minus sign character ('-'). Each specification starts
with a letter and may include other information after the letter to
define some aspect of the data layout. The specifications accepted are
as follows:

http://reviews.llvm.org/D8230

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/