Added auto_index
diff --git a/man/auto_index.Rd b/man/auto_index.Rd
new file mode 100644
index 0000000..abec3be
--- /dev/null
+++ b/man/auto_index.Rd
@@ -0,0 +1,16 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/group_rows.R
+\name{auto_index}
+\alias{auto_index}
+\title{Automatically figuring out the group_row index}
+\usage{
+auto_index(x)
+}
+\arguments{
+\item{x}{The index column. A vector. For example `c("a", "a", "b", "b", "b")``}
+}
+\description{
+This helper function allows users to build the \code{group_row}
+index more quickly and use \code{group_rows} in a way that is similar with
+\code{collapse_rows}.
+}