Add release notes for MLIR

Differential Revision: https://reviews.llvm.org/D156253

Author: joker-eph

mlir/docs/ReleaseNotes.md

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+# MLIR Release Notes
+
+This document tries to provide some context about MLIR important changes in the
+context of LLVM releases. It is updated on a best effort basis.
+
+At the moment the MLIR community does not qualify the LLVM release branch
+specifically, it is a snapshot of the MLIR development at the time of the release.
+
+\[TOC\]
+
+## LLVM 17
+
+See also the [deprecations and refactoring](https://mlir.llvm.org/deprecation/) doc.
+
+### Bytecode
+
+MLIR now support a [bytecode serialization](https://mlir.llvm.org/docs/BytecodeFormat/)
+with versionning compatibility allowing 2 ways compatibility scheme, and lazy-loading
+capabilities.
+
+### Properties: beyond attributes
+
+This is a new mechanism to implement storage for operations without having to
+use attributes. You can opt-in to use Properties for ODS inherent attributes
+using `let usePropertiesForAttributes = 1;` in your dialect definition (the flag
+will be default in the next release). See
+[slides](https://mlir.llvm.org/OpenMeetings/2023-02-09-Properties.pdf) and
+[recording](https://youtu.be/7ofnlCFzlqg) of the open meeting presentation for
+details.
+
+### Action: Tracing and Debugging MLIR-based Compilers
+
+[Action](https://mlir.llvm.org/docs/ActionTracing/) is a new mechanism to
+encapsulate any transformation of any granularity in a way that can be
+intercepted by the framework for debugging or tracing purposes, including
+skipping a transformation programmatically (think about “compiler fuel” or
+“debug counters” in LLVM). As such, “executing a pass” is an Action, so is “try
+to apply one canonicalization pattern”, or “tile this loop”.
+
+[slides](https://mlir.llvm.org/OpenMeetings/2023-02-23-Actions.pdf) and
+[recording](https://youtu.be/ayQSyekVa3c) of the open meeting presentation for
+details.
+
+### Transform Dialect
+
+See this [EuroLLVM talk](https://www.youtube.com/watch?v=P4gUj3QtH_Y&t=1s) and
+[the online tutorial](https://mlir.llvm.org/docs/Tutorials/transform/).
+
+### Others
+
+- There is now support for
+  "[distinct attributes](https://mlir.llvm.org/docs/Dialects/Builtin/#distinctattribute)".
+- "Resources" (a way to store data outside the MLIR context) and "configuration"
+  can now be serialized alongside the IR.