docs: mention subcommands in release notes, use for all 2.0 releases

relnotes/v2.0.0.md → relnotes/v2.0.md

@@ -1,4 +1,4 @@
-## Major changes in 2.0.0
+## Major changes in 2.0
 
 - Database backend switched from LevelDB to SQLite. There is a migration on
   first launch which can be lengthy for larger setups. The new database is
@@ -12,8 +12,9 @@
 
 - Modernised command line options parsing. Old single-dash long options are
   no longer supported, e.g. `-home` must be given as `--home`. Some options
-  have been renamed. All serve options are now also accepted as environment
-  variables. See `syncthing serve --help` for details.
+  have been renamed, others have become subcommands. All serve options are
+  now also accepted as environment variables. See  `syncthing --help` and
+  `syncthing serve --help` for details.
 
 - Rolling hash detection of shifted data is no longer supported as this
   effectively never helped. Instead, scanning and syncing is faster and more