doc: manifest.md add explain about double-bracket

diff --git a/src/doc/manifest.md b/src/doc/manifest.md
index b498963caf41b3ad0205d5c6ca259a54918d0ca9..197dff5b79797c4a59d4c41ecd00becca890bd55 100644 (file)
--- a/src/doc/manifest.md
+++ b/src/doc/manifest.md
@@ -468,7 +468,11 @@ the test files.
 
 All of the  `[[bin]]`, `[lib]`, `[[bench]]`, `[[test]]`, and `[[example]]`
 sections support similar configuration for specifying how a target should be
-built. The example below uses `[lib]`, but it also applies to all other sections
+built. The double-bracket sections like `[[bin]]` are array-of-table of
+[TOML](https://github.com/toml-lang/toml#array-of-tables), which means you can
+wirte more than one `[[bin]]` sections to make serval executables in your crate.
+
+The example below uses `[lib]`, but it also applies to all other sections
 as well. All values listed are the defaults for that option unless otherwise
 specified.