Fix php hightlight

[erasin]

namespace
fucntion

[the-mikedavis]

for code like

$array = ['One', 'Two', 'Three'];
echo $array[0]; // => "One"

This now highlights arrays in L2 as constant.builtin but I think the variable capture from before was more accurate

[erasin]

(subscript_expression
  (variable_name(name) @constant.builtin
    (#match? @constant.builtin "^_?[A-Z][A-Z\\d_]+$")))

it‘s seem ok

[the-mikedavis]

Looks great, thanks!