unix: fix name of generated zerrors_*.go in README

Change-Id: I31b9003abfe67ca2cbb9fc8ed68f612bf24cbfc0
Reviewed-on: https://go-review.googlesource.com/c/sys/+/227539
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/README.md

diff --git a/unix/README.md b/unix/README.md
index ab433cc..579d2d7 100644
--- a/unix/README.md
+++ b/unix/README.md
@@ -89,7 +89,7 @@
 
 Adding new syscall numbers is mostly done by running the build on a sufficiently
 new installation of the target OS (or updating the source checkouts for the
-new build system). However, depending on the OS, you make need to update the
+new build system). However, depending on the OS, you may need to update the
 parsing in mksysnum.
 
 ### mksyscall.go
@@ -163,7 +163,7 @@
 
 ## Generated files
 
-### `zerror_${GOOS}_${GOARCH}.go`
+### `zerrors_${GOOS}_${GOARCH}.go`
 
 A file containing all of the system's generated error numbers, error strings,
 signal numbers, and constants. Generated by `mkerrors.sh` (see above).