Set COLUM_WIDTHS for :help completion

Fixes #2287

CHANGELOG.asciidoc

@@ -60,6 +60,7 @@ Fixed
 - Fixed crashes when closing tabs while hinting
 - Fixed starting on newer PyQt/sip versions with LibreSSL
 - When downloading files with QtWebKit, a User-Agent header is set when possible.
+- Fixed showing of keybindings in the :help completion
 
 v0.9.1
 ------

qutebrowser/completion/models/miscmodels.py

@@ -53,6 +53,8 @@ class HelpCompletionModel(base.BaseCompletionModel):
     # https://github.com/qutebrowser/qutebrowser/issues/545
     # pylint: disable=abstract-method
 
+    COLUMN_WIDTHS = (20, 60, 20)
+
     def __init__(self, parent=None):
         super().__init__(parent)
         self._init_commands()