Typos correction

include/navigating-the-editor.html

@@ -57,7 +57,7 @@
 <h2>Zooming</h2>
 
 <p>
-  Zooming (on time) can be done on-canvas (which will always be centerd around the mouse cursor),
+  Zooming (on time) can be done on-canvas (which will always be centered around the mouse cursor),
   with the Summary, or with the <a href="@@zoom-controls">Zoom Controls</a>.
 </p>
 

include/ruler.html

@@ -6,7 +6,7 @@
 </p>
 
 <p>
-  It is made of a succession of rows, each having a special role related to time.From top to bottom, those rows are:
+  It is made of a succession of rows, each having a special role related to time. From top to bottom, those rows are:
 </p>
 
 <table class="dl">
@@ -23,4 +23,3 @@
 <p>
   Most of the operations on the markers are described in <a href="@@working-with-markers">Working with Markers</a>, while the Meter, Tempo, Bars:Beats and Timecode use are described in <a href="@@tempo-and-meter">Tempo and Meter</a>.
 </p>
-

include/toolbox.html

@@ -35,7 +35,7 @@
   for details.
 </p>
 
-<h2>The <em>Smart</em> switch
+<h2>The <em>Smart</em> switch</h2>
 
 <p>
   The <dfn>Smart Mode</dfn> button to the left of the mouse mode buttons
@@ -103,4 +103,3 @@
   cross-hairs. This tool acts on region gain and automation as the Draw tool.<br>
   On a MIDI region, it allows to lasso-select multiple notes at a time.</td></tr>
 </table>
-