Try letter-numbered nested list again

Author: AlexeySachkov

sycl/doc/design/SYCL2020-SpecializationConstants.md

@@ -323,10 +323,10 @@ different translation units, so it happens in `sycl-post-link` tool.
 There is a `SpecConstantsPass` LLVM IR pass which:
 1. Assigns numeric IDs to specialization constants found in the linked module.
 2. Transforms IR to either:
-   1. The form expected by the SPIR-V translator (format of the
+   a. The form expected by the SPIR-V translator (format of the
      expected IR is covered in "Transformation of LLVM IR to SPIR-V friendly IR
      form" section).
-   2. The form which is used for emulating specialization constants.
+   b. The form which is used for emulating specialization constants.
 3. Collects and provides \<Symbolic ID\> =\> \<numeric IDs + additional info\>
    mapping, which is later being used by DPC++ RT to set specialization constant
    values provided by user (section "Collecting spec constants info and
@@ -379,7 +379,7 @@ contains another composite within it, that nested composite is also being
 specialization constants. This done by depth-first search through the composite
 elements.
 
-#### 2.1 Transformation of LLVM IR to SPIR-V friendly IR form
+#### 2.a Transformation of LLVM IR to SPIR-V friendly IR form
 
 SPIR-V friendly IR form is a special representation of LLVM IR, where some
 function are named in particular way in order to be recognizable by the SPIR-V
@@ -446,7 +446,7 @@ LLVM IR generated by `SpecConstantsPass`:
 %gold = call %struct.POD __spirv_SpecConstantComposite([2 x %struct.A] %gold_POD_A, <2 x i32> %gold_POD_b)
 ```
 
-#### 2.2 Transformation of LLVM IR for emulating specialization constants
+#### 2.b Transformation of LLVM IR for emulating specialization constants
 
 In case we are not targeting SPIR-V, we don't have a native support for
 specialization constants and have to emulate them somehow. As stated above, it