Remove commas from method syntax

examples/array_methods.ion

examples/function_piping.ion

examples/let.ion

examples/methods.ion

examples/script_exec/array_methods.ion

manual/src/expansions/05-method.md

src/lib/parser/shell_expand/mod.rs

src/lib/parser/shell_expand/words/mod.rs

src/lib/parser/shell_expand/words/tests.rs