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

test/test_verilog_verilator_options.vader

@@ -0,0 +1,25 @@
+Before:
+  Save g:ale_verilog_verilator_options
+  let g:ale_verilog_verilator_options = ''
+
+After:
+  Restore
+  call ale#linter#Reset()
+
+Execute(Set Verilog Verilator linter additional options to `-sv --default-language "1800-2012"`):
+  runtime! ale_linters/verilog/verilator.vim
+
+  " Additional args for the linter
+  let g:ale_verilog_verilator_options = '-sv --default-language "1800-2012"'
+
+  call ale#Lint()
+
+  let g:run_cmd = ale_linters#verilog#verilator#GetCommand(bufnr(''))
+  let g:matched = match(g:run_cmd, '\s' . g:ale_verilog_verilator_options . '\s')
+
+  " match returns -1 if not found
+  AssertNotEqual
+  \   g:matched ,
+  \   -1 ,
+  \  'Additionnal arguments not found in the run command'
+