Update CHANGELOG

Author: José Valim

CHANGELOG.md

@@ -116,6 +116,23 @@ Percentage | Module
     77.19% | Total
 ```
 
+## v1.7.2 (2018-08-05)
+
+### 1. Bug fixes
+
+#### Elixir
+
+  * [DateTime] Take negative years into account in `DateTime.from_iso8601/1`
+  * [Kernel] Do not emit warnings for repeated docs over different clauses due to false negatives
+
+#### Mix
+
+  * [mix compile] Properly mark top-level dependencies as optional and as runtime. This fixes a bug where Mix attempted to start optional dependencies of a package when those optional dependencies were not available
+  * [mix compile] Avoid deadlock when a timestamp later than current time is found
+  * [mix help] Show task and alias help when both are available
+  * [mix test] Do not fail suite if there are no tests to run
+
+
 ## v1.7.1 (2018-07-26)
 
 ### 1. Bug fixes