Update CHANGELOG.md

Author: wannaphong

CHANGELOG.md

@@ -11,12 +11,17 @@ Notable changes between versions.
 - For full release notes, see:
   <https://github.com/PyThaiNLP/pythainlp/releases>
 - For detailed commit changes, see:
-  <https://github.com/PyThaiNLP/pythainlp/compare/v5.1.0...dev> (select tags to compare)
+  <https://github.com/PyThaiNLP/pythainlp/compare/v5.1.1...dev> (select tags to compare)
 
-## Version 5.1.0 -> Dev
+## Version 5.1.1 -> Dev
 
 [WIP]
 
+## Version 5.1.0 -> 5.1.1
+
+- PR Description: Refactor thai_consonants_all to Use set in syllable.py #1087
+- ThaiTransliterator: Select 1D CPU int64 tensor device #1089
+
 ## Version 5.0.5 -> 5.1.0
 
 - Add Thai Discourse Treebank postag #910