Continuous assignment from argumentless functions about style-guides HOT 2 OPEN

@nbdd0121 Disallowing argumentless functions would work. I don't see many people using them. It seems the best use-case is just for style consistency for a group of related functions.

For example: https://github.com/pulp-platform/riscv-dbg/blob/138d74bcaa90c70180c12215db3776813d2a95f2/src/dm_pkg.sv#L420-L437

 function automatic logic [31:0] csrr (csr_reg_t   csr,
                                        logic [4:0] dest);
    // rs1, CSRRS, rd, OpCode System
    return {csr, 5'h0, 3'h2, dest, 7'h73};
  endfunction

  function automatic logic [31:0] branch(logic [4:0]  src2,
                                         logic [4:0]  src1,
                                         logic [2:0]  funct3,
                                         logic [11:0] offset);
    // OpCode Branch
    return {offset[11], offset[9:4], src2, src1, funct3,
        offset[3:0], offset[10], 7'b11_000_11};
  endfunction

  function automatic logic [31:0] ebreak ();
    return 32'h00100073;
  endfunction

from style-guides.

By @a-will in #66 (comment)

// Equivalent variable declarations with initial values.
logic foo = bar;
var logic foo = bar;

// Equivalent net declarations with continuous assignment.
wire foo = bar;
wire logic foo = bar;

Wow, I didn't know you could do this. I think this example should be added to the "Use logic for synthesis" section. It may help stress the importance of the rule a bit more

from style-guides.