style-guide: refresh page: move ellipsis to a separate section and extend syntax (#9742)

* Move and reword ellipsis to a separate section

* Add notes about grouping placeholders

* Permit specifing repetition count for placeholders

* Mandate using simplified range syntax for ellipsis

* Update contributing-guides/style-guide.md

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

* Remove redundant note

* Refresh repetition syntax for ellipsis

* Don't allow restrict repetition count via ellipsis

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

contributing-guides/style-guide.md

@@ -160,6 +160,17 @@ All borders of integer and float ranges get included. If you want to exclude the
   using `{{*.ext}}` explains the command without being unnecessarily specific;
   while in `wc -l {{path/to/file}}` using `{{path/to/file}}` (without extension) is sufficient.
 
+### Grouping placeholders
+
+- If a command can take 0 or more arguments of the same kind, use an ellipsis: `{{placeholder1 placeholder2 ...}}`.
+  For instance, if multiple paths are expected `{{path/to/directory1 path/to/directory2 ...}}` can be used.
+- If a command can take 0 or more arguments of different kinds, use an ellipsis: `{{placeholder1|placeholder2|...}}`.
+  If there are more than 5 possible values use `|...` after the last item.
+- It's impossible to restrict the minimum or (and) maximum placeholder count via `ellipsis`.
+
+It's up to the program to decide how to handle duplicating values, provided syntax
+tells no info about whether items are mutually exclusive or not.
+
 ### Special cases
 
 - If a command performs irreversible changes to a file system or devices,
@@ -167,9 +178,6 @@ All borders of integer and float ranges get included. If you want to exclude the
   For example, instead of `ddrescue --force --no-scrape /dev/sda /dev/sdb`
   write `ddrescue --force --no-scrape {{/dev/sdX}} {{/dev/sdY}}`
   and use the `{{/dev/sdXY}}` placeholder for *block devices* instead of `/dev/sda1`.
-- If a command can take a variable number of arguments, use an ellipsis: `{{arg1 arg2 ...}}`.
-  If one of the multiple options is possible, write it as `{{either|or}}`.
-  If there are more than 5 alternatives, use `|...` for the ellipsis.
 
 In general, placeholders should make it as intuitive as possible
 to figure out how to use the command and fill it in with values.