Fix typos in Documentation/: 'H'-'M'

This patch fixes typos in various Documentation txts. The patch addresses
some words starting with the letters 'H'-'M'.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/video4linux/et61x251.txt b/Documentation/video4linux/et61x251.txt
index cd584f2..b65aa0f 100644
--- a/Documentation/video4linux/et61x251.txt
+++ b/Documentation/video4linux/et61x251.txt
@@ -80,7 +80,7 @@
   high compression quality (see also "Notes for V4L2 application developers"
   paragraph);
 - full support for the capabilities of every possible image sensors that can
-  be connected to the ET61X[12]51 bridges, including, for istance, red, green,
+  be connected to the ET61X[12]51 bridges, including, for instance, red, green,
   blue and global gain adjustments and exposure control (see "Supported
   devices" paragraph for details);
 - use of default color settings for sunlight conditions;