Add group metadata to EEP48

Also changed one item to keep order alphabetical.

lib/kernel/doc/guides/eep48_chapter.md

@@ -145,15 +145,20 @@ information to each entry. This EEP documents the following metadata keys:
   deprecated with a binary that represents the reason for deprecation and a
   recommendation to replace the deprecated code.
 
+- **`group := binary()`** - when present, it allows tooling, such as shell
+  autocompletion and documentation generators, to list all entries within the
+  same group together, often using the group name as an indicator. It currently
+  only applies to doc entries, not for module metadata.
+
 - **`since := binary()`** - a binary representing the version such entry was
   added, such as `<<"1.3.0">>` or `<<"20.0">>`.
 
-- **`source_path := binary()`** - the absolute location of the source file for
-  this module. Applies only to the module metadata.
-
 - **`source_annos := [erl_anno:anno()]`** - a list of source code locations.
   You may either store one for each clause or only for the first clause.
 
+- **`source_path := binary()`** - the absolute location of the source file for
+  this module. Applies only to the module metadata.
+
 Any key may be added to Metadata at any time. Keys that are frequently used by
 the community can be standardized in future versions.
 

system/doc/reference_manual/documentation.md

@@ -206,6 +206,9 @@ There are four reserved metadata keys for `-doc`:
   explaining that it is deprecated and what to use instead. The compiler will
   automatically insert this key if there is a `-deprecated` attribute marking a
   function as deprecated.
+- `group => unicode:chardata()` - A group that the function, type or callback belongs to.
+  It allows tooling, such as shell autocompletion and documentation generators, to list all
+  entries within the same group together, often using the group name as an indicator.
 - `equiv => unicode:chardata() | F/A | F(...)` - Notes that this function is equivalent to
   another function in this module. The equivalence can be described using either
   `Func/Arity`, `Func(Args)` or a [unicode string](`t:unicode:chardata/0`). For example: