change default `lsp_diag_virtual_text` prefix to nvim default (#353)

README.md

@@ -775,7 +775,7 @@ require('go').setup({
   lsp_diag_hdlr = true, -- hook lsp diag handler
   lsp_diag_underline = true,
   -- virtual text setup
-  lsp_diag_virtual_text = { space = 0, prefix = "" },
+  lsp_diag_virtual_text = { space = 0, prefix = '■' },
   lsp_diag_signs = true,
   lsp_diag_update_in_insert = false,
   lsp_document_formatting = true,

doc/go.txt

@@ -390,6 +390,7 @@ You can setup go.nvim with following options:
   lsp_keymaps = true, -- true: apply default lsp keymaps
   lsp_codelens = true,
   lsp_diag_hdlr = true, -- hook lsp diag handler
+  lsp_diag_virtual_text = { space = 0, prefix = '■' }, -- lsp virtual text format
   lsp_inlay_hints = {
     enable = true,
 

lua/go.lua

@@ -45,7 +45,7 @@ _GO_NVIM_CFG = {
   lsp_diag_hdlr = true, -- hook lsp diag handler
   lsp_diag_underline = true,
   -- virtual text setup
-  lsp_diag_virtual_text = { space = 0, prefix = '' },
+  lsp_diag_virtual_text = { space = 0, prefix = '■' },
   lsp_diag_signs = true,
   lsp_inlay_hints = {
     enable = true,