added message about versions

README.md

@@ -9,6 +9,34 @@ sily is a general-purpose library containing utilities for general programming a
 
 Documentation can be found [here](https://al1-ce.github.io/sily-docs/)
 
+## Versioning (Will be effective since 6.0) <!-- FIXME: Remove --> <!-- TODO: Remove -->
+Library follows semantic versioning (`x.y.z` where `x` is Major release, `y` is Minor release and `z` is Patch). This means that:
+- 1.0.Z - Patch version signified bugfixes and minor changes
+    - Patches are compatible with each other
+    - You can safely change from one patch to another
+    - You can specify version in project config file as {@s "~>x.y"}
+- 1.Y.0 - Minor version signifies new features
+    - Minor versions are not backwards-compatible
+    - You can safely upgrade from lower Minor release to higher Minor release
+    - You can specify version in project config file as {@s "~>x"} if you're using features only from first minor release
+- X.0.0 - Major version signifies breaking or removal of features
+    - Major releases are not compatible with each other
+    - You might have to fix your code in case of deprecations or major changes
+    - Deprecation will be removed in every Major release
+    - Deprecations will be introduces in Minor releases by tagging deprecated code with <code>{@t @}{@k deprecated}({@s "x.y.z - Why"})</code>, where {@s "x.y.z"} is version where code was deprecated and {@s "Why"} is reason for removal or what to use instead
+
+Example:
+```d
+Version 1.0.0 - Initial release
+Version 1.0.1 - Fixed functionA and structA
+Version 1.0.2 - Fixed functionB
+Version 1.1.0 - Moved functionB to moduleB
+                functionB marked @deprecated("1.1.0 - Moved to moduleB")
+Version 1.1.1 - Fixed functionC
+Version 1.2.0 - Added structB
+Version 2.0.0 - structA now has different logic. Removed functionB from moduleA
+```
+
 ## Development
 - [dmd / ldc / gdc](https://dlang.org/) - D compiler
 - [dub](https://code.dlang.org/) - D package manager