Fix FPDFAction_GetFilePath() documentation error.

Commit 5f597db5 accidentally changed this. Probably due to copy/pasting.

Change-Id: I41f6876da28d5d744d6d169c67b33399893e3585
Reviewed-on: https://pdfium-review.googlesource.com/6416
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/public/fpdf_doc.h b/public/fpdf_doc.h
index 9d55a2e..8e27223 100644
--- a/public/fpdf_doc.h
+++ b/public/fpdf_doc.h
@@ -138,10 +138,10 @@
 //   buffer - a buffer for output the path string. May be NULL.
 //   buflen - the length of the buffer, in bytes. May be 0.
 //
-// Returns the number of bytes in the file path, including the trailing UTF16
-// NUL character.
+// Returns the number of bytes in the file path, including the trailing NUL
+// character.
 //
-// Regardless of the platform, the |buffer| is always in UTF-16LE encoding.
+// Regardless of the platform, the |buffer| is always in UTF-8 encoding.
 // If |buflen| is less than the returned length, or |buffer| is NULL, |buffer|
 // will not be modified.
 DLLEXPORT unsigned long STDCALL