docs: reconfigure libbpf documentation syncing

This adds documentation files, including ones for autogenerating API
documentation based on code comments in the source code that's pulled
in via the mirror.

Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>

docs/api.rst

@@ -0,0 +1,51 @@
+.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+.. _api:
+
+.. toctree:: Table of Contents
+   
+
+LIBBPF API
+==================
+
+libbpf.h
+--------
+.. doxygenfile:: libbpf.h
+   :project: libbpf
+   :sections: func define public-type
+
+bpf.h
+-----
+.. doxygenfile:: bpf.h
+   :project: libbpf
+   :sections: func define public-type
+
+btf.h
+-----
+.. doxygenfile:: btf.h
+   :project: libbpf
+   :sections: func define public-type
+
+xsk.h
+-----
+.. doxygenfile:: xsk.h
+   :project: libbpf
+   :sections: func define public-type
+
+bpf_tracing.h
+-------------
+.. doxygenfile:: bpf_tracing.h
+   :project: libbpf
+   :sections: func define public-type
+
+bpf_core_read.h
+---------------
+.. doxygenfile:: bpf_core_read.h
+   :project: libbpf
+   :sections: func define public-type
+
+bpf_endian.h
+------------
+.. doxygenfile:: bpf_endian.h
+   :project: libbpf
+   :sections: func define public-type