Trivial update to meson vim syntax + typo in snippet [skip ci]

data/syntax-highlighting/vim/syntax/meson.vim

@@ -70,6 +70,7 @@ syn keyword mesonBuiltin
   \ add_project_link_arguments
   \ add_test_setup
   \ benchmark
+  \ both_libraries
   \ build_machine
   \ build_target
   \ configuration_data

docs/markdown/snippets/del-old-names.md

@@ -2,6 +2,6 @@
 
 Old executable names `mesonintrospect`, `mesonconf`, `mesonrewriter`
 and `mesontest` have been deprecated for a long time. Starting from
-this versino they no longer do anything but instead always error
+this version they no longer do anything but instead always error
 out. All functionality is available as subcommands in the main `meson`
 binary.