Add gen syscalls step to instructions.

Also, fix incorrect path to some tools.

(cherry picked from commit ea271fdf2671707ed29bc6b564f544d2489115ff)

Change-Id: Ie93cbc84b9a46d622b0b462a33bed0ee129992cb
diff --git a/libc/kernel/README.TXT b/libc/kernel/README.TXT
index 0edbcc6..e7312ef 100644
--- a/libc/kernel/README.TXT
+++ b/libc/kernel/README.TXT
@@ -55,11 +55,15 @@
 
 Grab the latest headers from the android kernel by running this command:
 
-  bionic/kernel/tools/generate_uapi_headers.sh --download-kernel
+  bionic/libc/kernel/tools/generate_uapi_headers.sh --download-kernel
 
 Next, run this command to copy the parsed files to bionic/libc/kernel/uapi:
 
-  bionic/kernel/tools/update_all.py
+  bionic/libc/kernel/tools/update_all.py
+
+Finally, run this command to regenerate the syscalls list:
+
+  bionic/libc/tools/gensyscalls.py
 
 After this, you will need to build/test the tree to make sure that these
 changes do not introduce any errors.