DOC: Update changelog for 0.15.2

Author: bluss

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "ndarray"
-version = "0.15.1"
+version = "0.15.2"
 edition = "2018"
 authors = [
   "bluss",

RELEASES.md

@@ -1,3 +1,46 @@
+Version 0.15.2 (2021-xx-xx Not released yet)
+===========================
+
+New features
+------------
+
+- New methods for growing/appending to owned `Array`s. These methods allow
+  building an array efficiently chunk by chunk. By [@bluss].
+
+  - `.push_row()`, `.push_column()`
+  - `.push(axis, array)`, `.append(axis, array)`
+
+  https://github.com/rust-ndarray/ndarray/pull/932 <br>
+  https://github.com/rust-ndarray/ndarray/pull/990
+
+- New reshaping method `.to_shape(...)`, called with new shape and optional
+  ordering parameter, this is the first improvement for reshaping in terms of
+  added features and increased consistency. By [@bluss].
+
+  https://github.com/rust-ndarray/ndarray/pull/982
+
+- `Array` now implements a by-value iterator, [by @bluss].
+
+  https://github.com/rust-ndarray/ndarray/pull/986
+
+Enhancements
+------------
+
+Bug fixes
+---------
+
+- Fix an error in construction of empty array with negative strides, by [@jturner314].
+
+  https://github.com/rust-ndarray/ndarray/pull/998
+
+API changes
+-----------
+
+
+Other changes
+-------------
+
+
 Version 0.15.1 (2021-03-29)
 ===========================