[Blob] Update documentation for is_binary. filter.h tells me that we check the first 8000 bytes.
diff --git a/include/git2/blob.h b/include/git2/blob.h
index 1b65833..c24ff7e 100644
--- a/include/git2/blob.h
+++ b/include/git2/blob.h
@@ -210,7 +210,7 @@ GIT_EXTERN(int) git_blob_create_frombuffer(
*
* The heuristic used to guess if a file is binary is taken from core git:
* Searching for NUL bytes and looking for a reasonable ratio of printable
- * to non-printable characters among the first 4000 bytes.
+ * to non-printable characters among the first 8000 bytes.
*
* @param blob The blob which content should be analyzed
* @return 1 if the content of the blob is detected