Add categories to changelog

CHANGELOG.md

@@ -1,7 +1,11 @@
 # v0.13
 
+## Interface
+
 Deadgrep now includes the result count in the mode line.
 
+## Keybindings
+
 **Changed default keybindings**: `n` and `p` are now bound to
 `deadgrep-forward-match` and `deadgrep-backward-match` respectively,
 so they only move through matches, ignoring buttons and file
@@ -21,6 +25,8 @@ To restore the old keybindings:
 Pressing RET on a column number now moves point directly the match,
 not just the beginning of the line.
 
+## Bugfixes
+
 Deadgrep now includes `--no-config` in its default arguments, so
 creating a `~/.ripgreprc` will not break deadgrep searches.