Docs for 7.x features (#9002)

- **docs: permissions**
- **docs: SQL COPY**
- **docs: Role.branches**
- **docs: Index.create_concurrently**

---------

Co-authored-by: dnwpark <dnwpark@protonmail.com>

Author: aljazerzen

docs/reference/ai/extai.rst

@@ -524,6 +524,8 @@ Example custom prompt configuration:
 Permissions
 ===========
 
+.. _ref_ai_extai_reference_permissions:
+
 .. versionadded:: 7.0
 
 .. list-table::

docs/reference/datamodel/index.rst

@@ -21,6 +21,7 @@ Schema
     aliases
     globals
     access_policies
+    permissions
     functions
     triggers
     mutation_rewrites

docs/reference/datamodel/indexes.rst

@@ -181,6 +181,50 @@ Example:
    }
 
 
+.. _ref_datamodel_indexes_concurrent:
+
+Concurrent index building
+=========================
+
+When creating an index, the object type will be locked for writes. This means
+that until the index is created, all ``insert``, ``update`` and ``delete``
+queries will be put on hold.
+On types containing many objects, this can span minutes or even hours.
+
+Instead, index building can be deferred from migration application to a later
+time. To do this, set ``build_concurrently`` index property to ``true``:
+
+.. code-block:: sdl
+
+   type User {
+     name: str;
+     index on (.name) {
+       build_concurrently := true;
+     };
+   }
+
+When this schema in applied to an instance, the index will be created, but it
+will not yet be active. The migration will not attempt to read any objects to
+build the index.
+
+As the last step of :gelcmd:`migration apply` (and :gelcmd:`migrate`), index
+will actually be built. During this time, the object type will not be locked
+for reads or writes.
+
+This means that migration will lock for significantly less time and allow index
+the be created while new writes are applied to the database.
+
+To apply migrations, but not build indexes at all, use
+:gelcmd:`migration apply --no-index-build` flag.
+This allows index building to be triggered at a later time,
+by using :gelcmd:`migration apply` again.
+
+Until the index is created, it will not be used to speed up queries.
+
+For tradeoffs of concurrent index building, refer to
+`PostgreSQL documentation <https://www.postgresql.org/docs/current/sql-createindex.html#SQL-CREATEINDEX-CONCURRENTLY>`_.
+
+
 Annotate an index
 =================
 
@@ -232,6 +276,11 @@ Syntax
   Allows setting index :ref:`annotation <ref_eql_sdl_annotations>` to a given
   value.
 
+- :sdl:synopsis:`build_concurrently := <bool>`
+
+  Allows index to be built
+  :ref:`after migration is applied <ref_datamodel_indexes_concurrent>`
+  to the instance.
 
 .. _ref_eql_ddl_indexes:
 
@@ -269,6 +318,12 @@ Creates a new index for a given object type or link using *index-expr*.
      Assign an annotation to this index.
      See :eql:stmt:`create annotation` for details.
 
+- :eql:synopsis:`set build_concurrently := <bool>`
+
+  Allows index to be built
+  :ref:`after migration is applied <ref_datamodel_indexes_concurrent>`
+  to the instance.
+
 Example:
 
 .. code-block:: edgeql