bump to v0.6.0 (update release_note)

Author: hymkor

release_note.md

@@ -1,3 +1,7 @@
+v0.6.0
+======
+Apr 22, 2023
+
 - Disable Ctrl-S and Ctrl-R (incremental search)
 - Add the option -submit-enter
 - Remove automatic-rollback on error because psql (PostgreSQL) does not do it
@@ -8,7 +12,7 @@
 
 v0.5.0
 ======
-Apr 19,2023
+Apr 19, 2023
 
 - `spool` writes program version also
 - Support Microsoft SQL Server