CHANGELOG.md: Start tracking user-visible changes for 0.3.6

Or whatever the next release ends up being.  It's easier to keep this
up to date as we go than to try and remember what the important
changes were when we cut the next release.

License: MIT
Signed-off-by: W. Trevor King

CHANGELOG.md

@@ -1,5 +1,14 @@
 # go-ipfs changelog
 
+### 0.3.6 - unreleased
+
+We don't know what the main changes will be yet.
+
+#### Stability and performance
+
+* prevent wantmanager from leaking goroutines (and
+  memory). @whyrusleeping, #1356
+
 ### 0.3.5 - 2015-06-11
 
 This patch improves overall stability and performance