Added first batch of feed icons (#708)

* Added first batch of feed icons

* Optimize SVGs

* Create eight-camels-shout.md

Co-authored-by: Julius Yanik <actions@github.com>
Co-authored-by: Ash Guillaume <10384315+ashygee@users.noreply.github.com>

Author: 3 people

.changeset/eight-camels-shout.md

@@ -0,0 +1,12 @@
+---
+"@primer/octicons": minor
+---
+
+Added first batch of 16px feed icons:
+- `feed-discussion`
+- `feed-heart`
+- `feed-person`
+- `feed-repo`
+- `feed-rocket`
+- `feed-star`
+- `feed-tag`