Documentation only, Terminal (#18696)

Add simple progress bar example to terminal module

lib/pure/terminal.nim

@@ -15,6 +15,21 @@
 ## code `exitprocs.addExitProc(resetAttributes)` to restore the defaults.
 ## Similarly, if you hide the cursor, make sure to unhide it with
 ## `showCursor` before quitting.
+##
+## Progress bar
+## ============
+##
+## Basic progress bar example:
+runnableExamples("-r:off"):
+  import std/[os, strutils]
+
+  for i in 0..100:
+    stdout.styledWriteLine(fgRed, "0% ", fgWhite, '#'.repeat i, if i > 50: fgGreen else: fgYellow, "\t", $i , "%")
+    sleep 42
+    cursorUp 1
+    eraseLine()
+
+  stdout.resetAttributes()
 
 ##[
 ## Playing with colorful and styled text
@@ -43,7 +58,6 @@ runnableExamples("-r:off"):
 
   stdout.styledWriteLine(fgRed, "red text ", styleBright, "bold red", fgDefault, " bold text")
 
-
 import macros
 import strformat
 from strutils import toLowerAscii, `%`