Remove trailing whitespace from all xfig files

The 5th line of every xfig file has 'Letter   ' which
annoys GITs trailing-whitespace commit hook. Hand edit
the files to remove that trailing whitespace

* docs/*.fig: Remove trailing whitespace

docs/architecture.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/libvirt-daemon-arch.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/libvirt-driver-arch.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/libvirt-net-logical.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/libvirt-net-physical.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/libvirt-object-model.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/migration-managed-direct.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/migration-managed-p2p.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/migration-native.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/migration-tunnel.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/migration-unmanaged-direct.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/node.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2

docs/structures.fig

@@ -2,7 +2,7 @@
 Landscape
 Center
 Inches
-Letter  
+Letter
 100.00
 Single
 -2