Update README

Signed-off-by: Dave Thaler <[email protected]>

Author: dthaler

README.md

@@ -3,10 +3,16 @@
 This repository is a working draft of standard eBPF documentation
 to be published by the eBPF Foundation in PDF format.
 
+Instruction Set Architecture:
+
 * [Current draft PDF](https://github.com/ebpffoundation/ebpf-docs/blob/pdf/instruction-set.pdf).
 * [Current Internet-Draft working copy](https://htmlpreview.github.io/?https://raw.githubusercontent.com/ebpffoundation/ebpf-docs/pdf/draft-thaler-bpf-isa.html)
 
-The authoritative source from which it is built is expected to be
+ELF File Format:
+
+* [Current Internet-Draft working copy](https://htmlpreview.github.io/?https://raw.githubusercontent.com/ebpffoundation/ebpf-docs/pdf/draft-thaler-bpf-elf.html)
+
+The authoritative source from which these are built is expected to be
 in the Linux kernel.org repository, but not be Linux specific.
 
 A GitHub mirror should be used, as is presently done for libbpf and