message: Added documentation for the target field `required-features`.
diff: @@ -551,6 +551,24 @@ proc-macro = false
  harness = true
  ```
  +## The `required-features` field (optional)
  +
  +The `required-features` field specifies which features must be selected for the
  +target to be built. This is only relevant for the `[[bin]]`, `[[bench]]`,
  +`[[test]]`, and `[[example]]` sections, it has no effect on `[lib]`.
  +
  +```toml
  +[features]
  +# ...
  +postgres = []
  +sqlite = []
  +tools = []
  +
  +[[bin]]
  +# ...
  +required-features = ["postgres", "tools"]
  +```
  +
  # Building dynamic or static libraries
  If your project produces a library, you can specify which kind of library to
  