Add changelog for 3.8.0-RC3

Signed-off-by: Wojciech Mazur <wmazur@virtuslab.com>

Author: WojciechMazur

changelogs/3.8.0-RC2.md

@@ -1,4 +1,4 @@
-# Backported chnages
+# Backported changes
 
 - Upgrade ASM to 9.9 for JDK 26 support [#24430](https://github.com/scala/scala3/pull/24430)
 - Bump Scala CLI to 1.10.1 (was 1.10.0) [#24448](https://github.com/scala/scala3/pull/24448)

changelogs/3.8.0-RC3.md

@@ -0,0 +1,33 @@
+# Backported changes
+
+- Fix #24599: Remove `| Null` from implicit BigDecimal conversion similar to BigInt [#24600](https://github.com/scala/scala3/pull/24600)
+- Fix #24571: Handling nullable types in convertTo for adapting number constants to target number types [#24580](https://github.com/scala/scala3/pull/24580)
+- Fix #24547: Strip inferred retains annotation from Macro/inline call trees [#24560](https://github.com/scala/scala3/pull/24560)
+- Allow annotations to annotate themselves [#24447](https://github.com/scala/scala3/pull/24447)
+- Allow to generate the documentation of the stdlib [#24574](https://github.com/scala/scala3/pull/24574)
+- Avoid blowup of compute times for ill-formed retains [#24564](https://github.com/scala/scala3/pull/24564)
+- Cleanups and source compatibility improvements for repl.AbstractFileClassLoader  [#24514](https://github.com/scala/scala3/pull/24514)
+- Deprecate the content of the `scala.runtime.stdLibPatches` package [#24587](https://github.com/scala/scala3/pull/24587)
+- Do not add `scala.util.Properties` as the Main-Class in the Manifest [#24540](https://github.com/scala/scala3/pull/24540)
+- Drop `-Yno-stdlib-patches` [#24477](https://github.com/scala/scala3/pull/24477)
+- Fix generic signatures for mixin forwarders conflicting type parameter names [#24567](https://github.com/scala/scala3/pull/24567)
+- Look at the underlying of a TermRef for a getter [#24565](https://github.com/scala/scala3/pull/24565)
+- Make `compilationUnitInfo` of `TastyLoader` lazy [#24604](https://github.com/scala/scala3/pull/24604)
+- Make `scala.Predef` capture checked [#24643](https://github.com/scala/scala3/pull/24643)
+- Refine parameter adaptation logic for arrays  [#23591](https://github.com/scala/scala3/pull/23591)
+- Strip CC annotations in TypeMap when CC is not enabled [#24556](https://github.com/scala/scala3/pull/24556)
+
+# Contributors
+
+Thank you to all the contributors who made this release possible 🎉
+
+According to `git shortlog -sn --no-merges 3.8.0-RC2..3.8.0-RC3` these are:
+
+```
+    22  Hamza Remmal
+    10  Wojciech Mazur
+     6  noti0na1
+     3  Matt Bovel
+     2  Martin Odersky
+     1  Oliver Bračevac
+```