Revert "all: use fixdocs tool to store package documentation in doc.go"

This reverts commit 963877e5f5.

floats/floats.go

@@ -2,6 +2,12 @@
 // Use of this code is governed by a BSD-style
 // license that can be found in the LICENSE file
 
+// Package floats provides a set of helper routines for dealing with slices
+// of float64. The functions avoid allocations to allow for use within tight
+// loops without garbage collection overhead.
+//
+// The convention used is that when a slice is being modified in place, it has
+// the name dst.
 package floats // import "gonum.org/v1/gonum/floats"
 
 import (