docs: add changelog and update README to reference it

Author: PrashamTrivedi

.github/.prompts/changelog.prompt.md

@@ -0,0 +1,25 @@
+UPDATE changelog to include changes between given tag/commit and latest tag.
+Make sure we follow reverse chronological order. Each tag should be their own h2
+header and under the tag, we list the changes made since given tag. If there is
+no given tag, consider the changelog against the latest master commit. And keep
+them under `Unreleased` h2 header.
+
+Under each h2 header, we can have the following sections:
+
+```md
+## [Unreleased OR tag]
+
+### Added
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security
+```
+
+UPDATE readme to reflect those changes for the first time visitor.

CHANGELOG.md

@@ -0,0 +1,15 @@
+# Changelog
+
+## [Unreleased]
+
+### Added
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security

README.md

@@ -142,6 +142,10 @@ server binary and ensure the `VAL_TOWN_API_TOKEN` environment variable is set.
 
 Contributions are welcome! Please feel free to submit a Pull Request.
 
+## Changelog
+
+See the [CHANGELOG](CHANGELOG.md) for a list of notable changes to this project.
+
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file