rebase and RST -> markdown plaintext syntax

Author: DavidSpickett

llvm/docs/ReleaseNotes.md

@@ -231,12 +231,12 @@ Changes to the C API
 * The following functions are added to allow iterating over debug records attached to
   instructions:
 
-  * ``LLVMGetFirstDbgRecord``
-  * ``LLVMGetLastDbgRecord``
-  * ``LLVMGetNextDbgRecord``
-  * ``LLVMGetPreviousDbgRecord``
+  * `LLVMGetFirstDbgRecord`
+  * `LLVMGetLastDbgRecord`
+  * `LLVMGetNextDbgRecord`
+  * `LLVMGetPreviousDbgRecord`
 
-* Added ``LLVMAtomicRMWBinOpUSubCond`` and ``LLVMAtomicRMWBinOpUSubSat`` to ``LLVMAtomicRMWBinOp`` enum for AtomicRMW instructions.
+* Added `LLVMAtomicRMWBinOpUSubCond` and `LLVMAtomicRMWBinOpUSubSat` to `LLVMAtomicRMWBinOp` enum for AtomicRMW instructions.
 
 Changes to the CodeGen infrastructure
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