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>
diff --git a/docs/.gitignore b/docs/.gitignore
new file mode 100644
index 0000000..dd08fae
--- /dev/null
+++ b/docs/.gitignore
@@ -0,0 +1,2 @@
+sphinx/build
+sphinx/doxygen/build
\ No newline at end of file