[Completion] fix missing space after 'if' in always* completions

[donlon]

Hi, thank you for this cool plugin! It has been a great help to my work.
I made a fix that a missing space is added in this completion.

always_ff @(posedge clk or negedge rst_n) begin : proc_
    if(~rst_n) begin
//    ^ space is added here
         <= 0;
    end else begin

    end
end