Documentation: remove duplicated words

Remove many duplicated words under Documentation/ and do other small
cleanups.

Examples:
        "and and" --> "and"
        "in in" --> "in"
        "the the" --> "the"
        "the the" --> "to the"
        ...

Signed-off-by: Paolo Ornati <ornati@fastwebnet.it>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/networking/s2io.txt b/Documentation/networking/s2io.txt
index bd528ff..4bde53e 100644
--- a/Documentation/networking/s2io.txt
+++ b/Documentation/networking/s2io.txt
@@ -126,7 +126,7 @@
 #setpci -d 17d5:* LATENCY_TIMER=f8
 For detailed description of the PCI registers, please see Xframe User Guide.
 b. Use 2-buffer mode. This results in large performance boost on
-on certain platforms(eg. SGI Altix, IBM xSeries).
+certain platforms(eg. SGI Altix, IBM xSeries).
 c. Ensure Receive Checksum offload is enabled. Use "ethtool -K ethX" command to 
 set/verify this option.
 d. Enable NAPI feature(in kernel configuration Device Drivers ---> Network