[AMDGPU][MC][DOC] Updated AMD GPU assembler syntax description.

Summary of changes:
- added description of GFX10;
- added description of operands sccz, vccz, lds_direct, etc;
- minor bugfixing and improvements.

llvm-svn: 365347
GitOrigin-RevId: cef9d42157e568eb1d87208be630a4185c675a26
diff --git a/docs/AMDGPU/gfx10_dst_mimg_regular.rst b/docs/AMDGPU/gfx10_dst_mimg_regular.rst
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+..
+    **************************************************
+    *                                                *
+    *   Automatically generated file, do not edit!   *
+    *                                                *
+    **************************************************
+
+.. _amdgpu_synid10_dst_mimg_regular:
+
+vdst
+===========================
+
+Image data to load by an image instruction.
+
+*Size:* depends on :ref:`dmask<amdgpu_synid_dmask>` and :ref:`tfe<amdgpu_synid_tfe>`:
+
+* :ref:`dmask<amdgpu_synid_dmask>` may specify from 1 to 4 data elements. Each data element occupies 1 dword.
+* :ref:`tfe<amdgpu_synid_tfe>` adds 1 dword if specified.
+
+*Operands:* :ref:`v<amdgpu_synid_v>`