Update comments on allowable_encoder_error

We're setting a value outside the currently documented value for y2016.

Change-Id: Idc6ca14698b13d2b5ff02c3c00c29cffa53331ef
diff --git a/frc971/zeroing/zeroing.cc b/frc971/zeroing/zeroing.cc
index 2284bde..4ff6391 100644
--- a/frc971/zeroing/zeroing.cc
+++ b/frc971/zeroing/zeroing.cc
@@ -108,8 +108,7 @@
     // zeroed.
     zeroed_ = true;
     // Throw an error if first_start_pos is bigger/smaller than
-    // allowable_encoder_error_ * index_diff +
-    // start_pos.
+    // allowable_encoder_error_ * index_diff + start_pos.
     if (::std::abs(first_start_pos_ - start_pos_) >
         allowable_encoder_error_ * index_diff_) {
       if (!error_) {