describe upgrade path, deprecate from_bufread functions

Author: conradkleinespel

README.md

@@ -16,6 +16,8 @@ rpassword = "7.4"
 
 See examples and docs at [https://docs.rs/rpassword](https://docs.rs/rpassword).
 
+See the upgrade path in [UPGRADE.md](UPGRADE.md).
+
 ## License
 
 The source code is released under the Apache 2.0 license.

UPGRADE.md

@@ -0,0 +1,28 @@
+# Upgrade Policy for `rpassword`
+
+## Overview
+This policy outlines the versioning and upgrade path for `rpassword`.
+
+Please report any upgrading issues or feedback to the project's issue tracker.
+
+## Versioning Rules
+
+### Patch Versions (`x.y.Z`)
+- **Definition**: Bug fixes, performance improvements, and minor documentation updates.
+- **Compatibility**: Fully backward-compatible. No breaking changes.
+- **User Action**: Safe to upgrade without code modifications.
+
+### Minor Versions (`x.Y.z`)
+- **Definition**: New features, enhancements, and deprecations.
+- **Compatibility**: Backward-compatible. Deprecated APIs remain functional but emit warnings.
+- **User Action**:
+    1. Upgrade to the latest minor version.
+    2. Address deprecation warnings to prepare for the next major version.
+
+### Major Versions (`X.y.z`)
+- **Definition**: Breaking changes, API redesigns, or significant architectural shifts.
+- **Compatibility**: Not backward-compatible. Deprecated APIs may be removed.
+- **User Action**:
+    1. Upgrade to the latest minor version of the current major release.
+    2. Fix all deprecation warnings.
+    3. Upgrade to the next major version.