Add changelog (#26894)

* Add changelog

* Lint: remove trailing whitespace

* Update based on review feedback

* Remove branch tracking from inside the changelog.

* Factor out duplication

* Add instruction about using the same wording when backporting

* Formatting - 80 character wrap

* Clarify ambiguous language

* Remove instruction that is only relelvant to backports

* Revert "Remove instruction that is only relelvant to backports"

This reverts commit 31fe048a5ec5493cf1c8524db10769cd14d2be0d.

* Update wording baased on review feedback

* Add core contributors to audience

Co-authored-by: Trent Nelson <trent.a.b.nelson@gmail.com>

* Updated based on review feedback.
* Add noteworthy criteria.
* Move instructions to bottom (below changelog).
* Add detail to instructions.

* Update core contributors to contributors

Co-authored-by: mvines <mvines@gmail.com>

* Remove superfluous "ABI"

Co-authored-by: mvines <mvines@gmail.com>

* Add anchor link at the top to the instructions at the bottom

Co-authored-by: Trent Nelson <trent.a.b.nelson@gmail.com>

* Add instructions for maintaining the changelog

* wording. add entry for edge channel.

* switch language from "branches" to "channels"
* adds entry for edge channel

Co-authored-by: Trent Nelson <trent.a.b.nelson@gmail.com>

* Remove whitespace in link

---------

Co-authored-by: Trent Nelson <trent.a.b.nelson@gmail.com>
Co-authored-by: mvines <mvines@gmail.com>

CHANGELOG.md

@@ -0,0 +1,61 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+Please follow the [guidance](#adding-to-this-changelog) at the bottom of this file when making changes
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html)
+and follows a [Backwards Compatability Policy](https://docs.solana.com/developing/backwards-compatibility)
+
+Release channels have their own copy of this changelog:
+* [edge - v1.17](#edge-channel)
+* [beta - v1.16](https://github.com/solana-labs/solana/blob/v1.16/CHANGELOG.md)
+* [stable - v1.14](https://github.com/solana-labs/solana/blob/v1.14/CHANGELOG.md)
+
+<a name="edge-channel"></a>
+## [1.17.0] - Unreleased
+* Changes
+  * Added a changelog.
+* Upgrade Notes
+
+## Adding to this Changelog
+### Audience
+* Entries in this log are intended to be easily understood by contributors,
+consensus validator operators, rpc operators, and dapp developers.
+
+### Noteworthy
+* A change is noteworthy if it:
+  * Adds a feature gate, or
+  * Implements a SIMD, or
+  * Modifies a public API, or
+  * Changes normal validator / rpc run configurations, or
+  * Changes command line arguments, or
+  * Fixes a bug that has received public attention, or
+  * Significantly improves performance, or
+  * Is authored by an external contributor.
+
+### Instructions
+* Update this log in the same pull request that implements the change. If the
+change is spread over several pull requests update this log in the one that
+makes the feature code complete.
+* Add notes to the [Unreleased] section in each branch that you merge to.
+  * Add a description of your change to the Changes section.
+  * Add Upgrade Notes if the change is likely to require:
+    * validator or rpc operators to update their configs, or
+    * dapp or client developers to make changes.
+* Link to any relevant feature gate issues or SIMDs.
+* If you add entries on multiple branches use the same wording if possible.
+This simplifies the process of diffing between versions of the log.
+
+## Maintaining This Changelog
+### When creating a new release branch:
+* Commit to master updating the changelog:
+  * Remove `Unreleased` annotation from vx.y.0 section.
+  * Create new section: `vx.y+1.0 - Unreleased`
+* Create vx.y branch starting at that commit
+* Tag that commit as vx.y.0
+
+### When creating a new patch release:
+* Commit to the release branch updating the changelog:
+  * Remove `Unreleased` annotation from `vx.y.z` section
+  * Add a new section at the top for `vx.y.z+1 - Unreleased`
+* Tag that new commit as the new release