Adds an option to pass additional arguments to the verilog/verilator … (#698)

* Adds an option to pass additional arguments to the verilog/verilator linter

The new otion is g:ale_verilog_verilator_options
+ doc

* Spell check verilog linter doc file

* Add entries to the verilog linters in the doc table of content

* Vader test for verilog/verilator linter args option verilog_verilator_options

doc/ale.txt

@@ -101,6 +101,9 @@ CONTENTS                                                         *ale-contents*
       eslint..............................|ale-typescript-eslint|
       tslint..............................|ale-typescript-tslint|
       tsserver............................|ale-typescript-tsserver|
+    verilog/systemverilog.................|ale-verilog-options|
+      iverilog............................|ale-verilog-iverilog|
+      verilator...........................|ale-verilog-verilator|
     vim...................................|ale-vim-options|
       vint................................|ale-vim-vint|
     xml...................................|ale-xml-options|