Update refpage short descriptions of VkAttachmentLoad/StoreOp to be c…

…onsistent with spec body (#2364)

chapters/renderpass.adoc

@@ -5492,7 +5492,7 @@ cannot safely access values outside of the render area during a render pass
 instance when a load operation that modifies values is used.
 ====
 
-[open,refpage='VkAttachmentLoadOp',desc='Specify how contents of an attachment are initialized at the beginning of a subpass',type='enums']
+[open,refpage='VkAttachmentLoadOp',desc='Specify how contents of an attachment are treated at the beginning of the subpass where it is first used',type='enums']
 --
 Load operations that can: be used for a render pass are:
 
@@ -5591,7 +5591,7 @@ during a render pass instance when a store operation that modifies values is
 used.
 ====
 
-[open,refpage='VkAttachmentStoreOp',desc='Specify how contents of an attachment are stored to memory at the end of a subpass',type='enums']
+[open,refpage='VkAttachmentStoreOp',desc='Specify how contents of an attachment are treated at the end of the subpass where it is last used',type='enums']
 --
 Possible values of slink:VkAttachmentDescription::pname:storeOp and
 pname:stencilStoreOp, specifying how the contents of the attachment are