[pitivi] docs: Add GSoCs 2019

[Alexandru Băluț <alexbalut src gnome org>]

commit e92dcd1978af4a55f16afb9ed9a13c85259659b3
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Mon Nov 25 00:02:41 2019 +0100

    docs: Add GSoCs 2019

 docs/Past_GSoCs.md | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/docs/Past_GSoCs.md b/docs/Past_GSoCs.md
index 97c48216..d62987e7 100644
--- a/docs/Past_GSoCs.md
+++ b/docs/Past_GSoCs.md
@@ -7,6 +7,16 @@ short-description: What the GSoC students did in the previous years
 See [Google Summer of Code](Google_Summer_of_Code.md) for how to
 get involved.
 
+## 2019
+
+-   [Millan Castro](https://millancv.github.io/) implemented [timeline
+    markers](https://millancv.github.io//GSoC-3/).
+-   [Swayamjeet Swain](https://swaynethoughts.wordpress.com/)
+    implemented support for [nested
+    timelines](https://swaynethoughts.wordpress.com/2019/08/25/gsoc-2019-final-report/).
+-   [Yatin Maan](https://yatinmaan.github.io/) improved the [effects
+    usability](https://yatinmaan.github.io/2019/08/26/GSoC-19-Final-Report/).
+
 ## 2018
 
 -   [Harish Fulara](https://harishfulara07.wordpress.com/) implemented