Fix wrong changelog format

Author: Aljullu

readme.txt

@@ -122,12 +122,12 @@ Release and roadmap notes available on the [WooCommerce Developers Blog](https:/
 = 2.5.9 - 2020-01-07 =
 - Fix issue in All Products block that was causing Variable products price to exclude taxes in some cases. #1503
 
-= 2.5.8 = 2020-01-02 =
+= 2.5.8 - 2020-01-02 =
 - Fixed a bug where Filter by Price didn't show up. #1450
 - Price filter now allows entering any number in the input fields, even if it's out of constrains. #1457
 - Make price slider accurately represent the selected price #1453
 
-= 2.5.7 = 2019-12-20 =
+= 2.5.7 - 2019-12-20 =
 - Add translation comments and use correct functions #1412, #1415
 - bug: Fix Price Filter constraints when price is decimal #1419