Documentation: bpf: Add implementation notes documentations to table of contents

Sphinx reported warnings on missing implementation notes documentations in the
table of contents:

Documentation/bpf/clang-notes.rst: WARNING: document isn't included in any toctree
Documentation/bpf/linux-notes.rst: WARNING: document isn't included in any toctree

Add these documentations to the table of contents (index.rst) of BPF
documentation to fix the warnings.

Link: https://lore.kernel.org/linux-doc/[email protected]/
Fixes: 6c7aaff ("bpf, docs: Move Clang notes to a separate file")
Fixes: 6166da0 ("bpf, docs: Move legacy packet instructions to a separate file")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Bagas Sanjaya <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: bagasme

Documentation/bpf/index.rst

@@ -26,6 +26,8 @@ that goes into great technical depth about the BPF Architecture.
    classic_vs_extended.rst
    bpf_licensing
    test_debug
+   clang-notes
+   linux-notes
    other
 
 .. only::  subproject and html