style: update gitignore and add editor/editorconfig settings

.editorconfig

@@ -0,0 +1,25 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[cmd/txttocode/txt/*.txt]
+charset = unset
+end_of_line = unset
+indent_style = unset
+indent_size = unset
+trim_trailing_whitespace = unset
+insert_final_newline = unset
+
+[{*.go,go.{mod,work,work.sum,sum}}]
+indent_style = tab
+indent_size = 2
+tab_width = 2
+
+[*.md]
+trim_trailing_whitespace = false