Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt
index 2d78f19..d4d41465 100644
--- a/Documentation/filesystems/squashfs.txt
+++ b/Documentation/filesystems/squashfs.txt
@@ -219,7 +219,7 @@
 reference to where the actual value is stored).  This allows large values
 to be stored out of line improving scanning and lookup performance and it
 also allows values to be de-duplicated, the value being stored once, and
-all other occurences holding an out of line reference to that value.
+all other occurrences holding an out of line reference to that value.
 
 The xattr lists are packed into compressed 8K metadata blocks.
 To reduce overhead in inodes, rather than storing the on-disk