fix(volo-thrift): fix clippy lint too_long_first_doc_paragraph

[yukiiiteru]

Motivation

https://rust-lang.github.io/rust-clippy/master/index.html#/too_long_first_doc_paragraph

$ cargo clippy -p volo-thrift --no-default-features -- --deny warnings
    Checking volo v0.10.2 (/root/volo/volo)
error: first doc comment paragraph is too long
  --> volo/src/discovery/mod.rs:66:1
   |
66 | / /// [`diff_address`] provides a naive implementation that compares prev and next only by the
67 | | /// address, and returns the [`Change`], which means that the `updated` is always empty when using
68 | | /// this implementation.
69 | | ///
70 | | /// The bool in the return value indicates whether there's diff between prev and next, which means
   | |_
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph
   = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]`

error: could not compile `volo` (lib) due to 1 previous error


$ cargo clippy -p volo-thrift --no-default-features -- --deny warnings
    Checking volo-thrift v0.10.3 (/root/volo/volo-thrift)
error: first doc comment paragraph is too long
  --> volo-thrift/src/codec/default/mod.rs:48:1
   |
48 | / /// [`ZeroCopyEncoder`] tries to encode a message without copying large data taking the advantage
49 | | /// of [`LinkedBytes`], which can insert a [`Bytes`] into the middle of a [`bytes::BytesMut`] and
50 | | /// uses writev.
51 | | ///
52 | | /// The recommended length threshold to use `LinkedBytes::insert` is 4KB.
   | |_
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph
   = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]`

error: first doc comment paragraph is too long
  --> volo-thrift/src/codec/default/mod.rs:77:1
   |
77 | / /// [`ZeroCopyDecoder`] tries to decode a message without copying large data, so the [`Bytes`] in
78 | | /// the `decode` method is not designed to be reused, and the implementation can use
79 | | /// `Bytes::split_to` to get a [`Bytes`] and hand it to the user directly.
   | |_
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph

error: could not compile `volo-thrift` (lib) due to 2 previous errors

Solution

Add short first doc paragraphs for those idents.