Merge pull request #4576 from ranguli/fix-documentation-typo

Fix small typo in the manual

app/resources/documentation/manual/index.md

@@ -193,7 +193,7 @@ Navigation in TrenchBroom is quite simple and straightforward. You will mostly u
 
 ### Looking and Moving Around
 
-In the 3D viewport, can look around by holding the right mouse button and dragging the mouse around. There are several ways to move the camera around. First and foremost, you can move the camera forward and backward in the viewing direction by spinning the scroll wheel. If you prefer to have the scroll wheel move the camera in the direction where the mouse cursor is pointing, you can check the "Move camera towards cursor" option in the preferences. To move the camera sideways and up / down, hold the middle mouse button and drag the mouse in any direction. For tablet users, there is an option in the preferences that will enable you to move the camera horizontally by holding #key(Alt). Additionally, you can use the following keyboard shortcuts:
+In the 3D viewport, you can look around by holding the right mouse button and dragging the mouse around. There are several ways to move the camera around. First and foremost, you can move the camera forward and backward in the viewing direction by spinning the scroll wheel. If you prefer to have the scroll wheel move the camera in the direction where the mouse cursor is pointing, you can check the "Move camera towards cursor" option in the preferences. To move the camera sideways and up / down, hold the middle mouse button and drag the mouse in any direction. For tablet users, there is an option in the preferences that will enable you to move the camera horizontally by holding #key(Alt). Additionally, you can use the following keyboard shortcuts:
 
 Direction    Key
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