bundles: clarify streaming v2 bundle usage

This seems useful to clarify through the documentation
(we were still using debugcreatestreamclonebundle, even though
'hg bundle' is already an option...).

hgext/clonebundles.py

@@ -79,8 +79,10 b' for most needs.'
 Bundle files can be generated with the :hg:`bundle` command. Typically
 :hg:`bundle --all` is used to produce a bundle of the entire repository.
 
-:hg:`debugcreatestreamclonebundle` can be used to produce a special
-*streaming clonebundle*. These are bundle files that are extremely efficient
+The bundlespec option `stream` (see :hg:`help bundlespec`)
+can be used to produce a special *streaming clonebundle*, typically using
+:hg:`bundle --all --type="none-streamv2"`.
+These are bundle files that are extremely efficient
 to produce and consume (read: fast). However, they are larger than
 traditional bundle formats and require that clients support the exact set
 of repository data store formats in use by the repository that created them.

mercurial/helptext/bundlespec.txt

@@ -67,6 +67,10 b' The following bundle <compression> engin'
 
 .. bundlecompressionmarker
 
+The compression engines can be prepended with ``stream`` to create a streaming bundle.
+These are bundles that are extremely efficient to produce and consume,
+but do not have guaranteed compatibility with older clients.
+
 Available Options
 =================
 
@@ -89,7 +93,6 b' phases'
 revbranchcache
     Include the "tags-fnodes" cache inside the bundle.
 
-
 tagsfnodescache
     Include the "tags-fnodes" cache inside the bundle.
 
@@ -109,3 +112,10 b' Examples'
 
 ``zstd-v1``
     This errors because ``zstd`` is not supported for ``v1`` types.
+
+``none-streamv2``
+    Produce a ``v2`` streaming bundle with no compression.
+
+``zstd-v2;obsolescence=true;phases=true``
+    Produce a ``v2`` bundle with zstandard compression which includes
+    obsolescence markers and phases.