Document the new write behaviour

doc/pages/changelog.asciidoc

@@ -19,6 +19,9 @@ released versions.
 * `write -atomic` was replaced with `write -method [replace|overwrite]` to
   make both write methods available explicitly
 
+* `write <filename>` will fail if the given filename already exists and is
+  a regular file. Use the `-force` switch to override that behaviour.
+
 == Kakoune 2020.09.01
 
 * The `repl` and `send-text` aliases have been renamed respectively into

src/main.cc

@@ -45,6 +45,7 @@ struct {
     StringView notes;
 } constexpr version_notes[] = { {
         0,
+        "» {+u}write <filename>{} will refuse to overwrite without {+u}-force{}\n"
         "» {+u}$kak_command_fifo{} support\n"
         "» {+u}set-option -remove{} support\n"
         "» prompts auto select {+i}menu{} completions on space\n"