Add Documentation (#13811)

* Add more Docs and runnableExamples

lib/std/editdistance.nim

@@ -13,10 +13,11 @@
 import unicode
 
 proc editDistance*(a, b: string): int {.noSideEffect.} =
-  ## Returns the unicode-rune edit distance between ``a`` and ``b``.
+  ## Returns the **unicode-rune** edit distance between ``a`` and ``b``.
   ##
   ## This uses the `Levenshtein`:idx: distance algorithm with only a linear
   ## memory overhead.
+  runnableExamples: static: doAssert editdistance("Kitten", "Bitten") == 1
   if len(a) > len(b):
     # make ``b`` the longer string
     return editDistance(b, a)
@@ -181,6 +182,7 @@ proc editDistanceAscii*(a, b: string): int {.noSideEffect.} =
   ##
   ## This uses the `Levenshtein`:idx: distance algorithm with only a linear
   ## memory overhead.
+  runnableExamples: static: doAssert editDistanceAscii("Kitten", "Bitten") == 1
   var len1 = a.len
   var len2 = b.len
   if len1 > len2: