Completed update logs

Author: Ang3

CHANGELOG.md

@@ -7,6 +7,7 @@ CHANGELOG
 * PHP 8 support
 * Symfony v6.x support
 * Removed CSV support (prefer using the Symfony encoder instead).
-* Added context parameter ```AS_COLLECION_KEY```
+* Deleted format ```ExcelEncoder::SPREADSHEET```
+* Added context parameter ```ExcelEncoder::AS_COLLECION_KEY```
 * Decoding without merging headers row (as no collection)
-* Removed context parameter ```NB_HEADER_ROWS_KEY```
+* Removed context parameter ```ExcelEncoder::NB_HEADER_ROWS_KEY```

UPGRADE-2.0.md

@@ -0,0 +1,17 @@
+UPGRADE FROM 1.x to 2.x
+=======================
+
+Binary compatibility break (BC break).
+
+**No CSV support anymore**
+
+Support
+-------
+
+- Do not use this encoder to encode/decode CSV data.
+- Replace the encoding format to ```ExcelEncoder::XLS``` or ```ExcelEncoder::XLSX```
+
+Context
+-------
+
+- Delete usage of context parameter ```ExcelEncoder::NB_HEADER_ROWS_KEY``` (int).