[Tracking] write rustdocs for functions

[dongsupark]

We already have comments for some functions, but not with the correct rustdocs format. ///
Current status:

• src/download.rs

  • hash_on_disk
  • download_and_hash

• src/request.rs

  • perform

• src/util.rs

  • retry_loop

• update-format-crau/src/delta_update.rs

  • read_delta_update_header
  • get_manifest_bytes
  • get_signatures_bytes
  • get_header_data_length
  • get_header_data_length
  • get_data_blobs
  • parse_signature_data
  • verify_sig_pubkey

• update-format-crau/src/verify_sig.rs

  • sign_rsa_pkcs
  • verify_rsa_pkcs_buf
  • verify_rsa_pkcs_prehash
  • get_private_key_pkcs_pem
  • get_public_key_pkcs_pem

• omaha/src/hash_types.rs

  • Hash::from_bytes
  • Hash::from_base64
  • Hash::from_hex

• omaha/src/types.rs

  • FileSize::from_bytes
  • FileSize::bytes

[Varnika060306]

Assign to me please

[dongsupark]

@Varnika060306 Sorry for late reply.
Which part exactly do you want to work on?

FYI @John15321 is currently experimenting Copilot-based rustdocs, for example #80 and #81.