Rename `write_ascii_table` to `write_plain_table`

core/text/table/doc.odin

@@ -59,7 +59,7 @@ This outputs:
 
 	build(tbl)
 
-	write_ascii_table(stdio_writer(), tbl)
+	write_plain_table(stdio_writer(), tbl)
 	write_markdown_table(stdio_writer(), tbl)
 
 This outputs:

core/text/table/table.odin

@@ -254,7 +254,7 @@ write_html_table :: proc(w: io.Writer, tbl: ^Table) {
 	io.write_string(w, "</table>\n")
 }
 
-write_ascii_table :: proc(w: io.Writer, tbl: ^Table) {
+write_plain_table :: proc(w: io.Writer, tbl: ^Table) {
 	if tbl.dirty {
 		build(tbl)
 	}