Update changelog

Signed-off-by: Lauris Bukšis-Haberkorns <lauris@nix.lv>

CHANGELOG.md

@@ -6,7 +6,7 @@ been added to each release, please refer to the [blog](https://blog.gitea.io).
 
 ## [1.5.0-RC1](https://github.com/go-gitea/gitea/releases/tag/v1.5.0-rc1) - 2018-07-04
 * SECURITY
-  * Limit uploaded avatar image-size to 4096x3072 by default (#4353)
+  * Limit uploaded avatar image-size to 4096px x 3072px by default (#4353)
   * Do not allow to reuse TOTP passcode (#3878)
 * FEATURE
   * Add cli commands to regen hooks & keys (#3979)