[llvm] [LangRef] Document the difference between `<abi>` and `<pref>` (PR #147929)

[Nikita Popov via llvm-commits]

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@@ -3261,8 +3272,8 @@ specifications are given in this list:
 -  ``i8:8:8`` - i8 is 8-bit (byte) aligned as mandated
 -  ``i16:16:16`` - i16 is 16-bit aligned
 -  ``i32:32:32`` - i32 is 32-bit aligned
--  ``i64:32:64`` - i64 has ABI alignment of 32-bits but preferred
-   alignment of 64-bits
+-  ``i64:32:64`` - i64 is aligned at 32-bits but should be aligned to
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nikic wrote:

I'd keep the old wording here.

https://github.com/llvm/llvm-project/pull/147929