message: changelog: fix issue links
  For some reason GitHub pull requests are linked as `/pull/N` but issues
  are `/issues/N`. This commit fixes the links in the CHANGELOG.
  PR
diff: @@ -6,7 +6,7 @@ compile on other Rust versions, such as Rust 1.39.
  Bug fixes:
  -* [BUG #685](https://github.com/rust-lang/regex/issue/685):
  +* [BUG #685](https://github.com/rust-lang/regex/issues/685):
  Remove use of `doc_comment` crate, which cannot be used before Rust 1.43.
  @@ -22,9 +22,9 @@ Bug fixes:
  * [BUG #523](https://github.com/rust-lang/regex/pull/523):
  Add note to documentation that spaces can be escaped in `x` mode.
  -* [BUG #524](https://github.com/rust-lang/regex/issue/524):
  +* [BUG #524](https://github.com/rust-lang/regex/issues/524):
  Add support for empty sub-expressions, including empty alternations.
  -* [BUG #659](https://github.com/rust-lang/regex/issue/659):
  +* [BUG #659](https://github.com/rust-lang/regex/issues/659):
  Fix match bug caused by an empty sub-expression miscompilation.
  