Implement Markdown definition lists (+ migration) (#20333)

Implements definition lists Markdown extension adopted in a few
implementations including:
* [Pandoc](
  https://pandoc.org/MANUAL.html#definition-lists)
* [kramdown](
  https://kramdown.gettalong.org/quickref.html#definition-lists)
* [PHP extra Markdown](
  https://michelf.ca/projects/php-markdown/extra/#def-list)

Also affected files have been migrated.
RST definition lists are turned off for Markdown: this solves the
problem of broken formatting mentioned in
https://github.com/nim-lang/Nim/pull/20292.

1 files changed, 14 insertions, 14 deletions

diff --git a/lib/impure/nre.nim b/lib/impure/nre.nim
index 1012c7c36..738fc39cf 100644
--- a/lib/impure/nre.nim
+++ b/lib/impure/nre.nim
@@ -75,16 +75,16 @@ type
     ## comment".`
     ##
     ## `pattern: string`
-    ##     the string that was used to create the pattern. For details on how
+    ## :   the string that was used to create the pattern. For details on how
     ##     to write a pattern, please see `the official PCRE pattern
     ##     documentation.
     ##     <https://www.pcre.org/original/doc/html/pcrepattern.html>`_
     ##
     ## `captureCount: int`
-    ##     the number of captures that the pattern has.
+    ## :   the number of captures that the pattern has.
     ##
     ## `captureNameId: Table[string, int]`
-    ##     a table from the capture names to their numeric id.
+    ## :   a table from the capture names to their numeric id.
     ##
     ##
     ## Options
@@ -151,36 +151,36 @@ type
     ## execution. On failure, it is none, on success, it is some.
     ##
     ## `pattern: Regex`
-    ##     the pattern that is being matched
+    ## :   the pattern that is being matched
     ##
     ## `str: string`
-    ##     the string that was matched against
+    ## :   the string that was matched against
     ##
     ## `captures[]: string`
-    ##     the string value of whatever was captured at that id. If the value
+    ## :   the string value of whatever was captured at that id. If the value
     ##     is invalid, then behavior is undefined. If the id is `-1`, then
     ##     the whole match is returned. If the given capture was not matched,
     ##     `nil` is returned. See examples for `match`.
     ##
     ## `captureBounds[]: HSlice[int, int]`
-    ##     gets the bounds of the given capture according to the same rules as
+    ## :   gets the bounds of the given capture according to the same rules as
     ##     the above. If the capture is not filled, then `None` is returned.
     ##     The bounds are both inclusive.  See examples for `match`.
     ##
     ## `match: string`
-    ##     the full text of the match.
+    ## :   the full text of the match.
     ##
     ## `matchBounds: HSlice[int, int]`
-    ##     the bounds of the match, as in `captureBounds[]`
+    ## :   the bounds of the match, as in `captureBounds[]`
     ##
     ## `(captureBounds|captures).toTable`
-    ##     returns a table with each named capture as a key.
+    ## :   returns a table with each named capture as a key.
     ##
     ## `(captureBounds|captures).toSeq`
-    ##     returns all the captures by their number.
+    ## :   returns all the captures by their number.
     ##
     ## `$: string`
-    ##     same as `match`
+    ## :   same as `match`
     pattern*: Regex  ## The regex doing the matching.
                      ## Not nil.
     str*: string  ## The string that was matched against.
@@ -583,11 +583,11 @@ proc find*(str: string, pattern: Regex, start = 0, endpos = int.high): Option[Re
   ## positions.
   ##
   ## `start`
-  ##     The start point at which to start matching. `|abc` is `0`;
+  ## :   The start point at which to start matching. `|abc` is `0`;
   ##     `a|bc` is `1`
   ##
   ## `endpos`
-  ##     The maximum index for a match; `int.high` means the end of the
+  ## :   The maximum index for a match; `int.high` means the end of the
   ##     string, otherwise it’s an inclusive upper bound.
   return str.matchImpl(pattern, start, endpos, 0)