Add info about removed warning (#484)
Add info about removed warning (#484)

* Update 03-parent-locale.md

This warning was removed in 2.16.0 (https://github.com/moment/moment/commit/a83615a3dfdef0f4ddda3a4bcdfc90028e158d07#diff-6d534a0c3c9df392784bdfbc68d046b3)

However, an exception was thrown when using a moment defined with non existent parent. This bug was fixed in PR #4310. This documentation reflects this.

* Update 03-parent-locale.md

* Update 03-parent-locale.md

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