add documentation about target.$triple.rustflags

diff --git a/src/doc/config.md b/src/doc/config.md
index 6a41019923a417b205a039a7fb10429ef0bb0ad2..c542af429eb392530f0d0eacb3dc8babe3a4325e 100644 (file)
--- a/src/doc/config.md
+++ b/src/doc/config.md
@@ -69,6 +69,9 @@ linker = ".."
 # Similar to the above linker configuration, but this only applies to
 # when the `$triple` is being compiled for.
 linker = ".."
+# custom flags to pass to all compiler invocations that target $triple
+# this value overrides build.rustflags when both are present
+rustflags = ["..", ".."]
 
 # Configuration keys related to the registry
 [registry]