environment variables -> environment

As @sanxiyn says,
https://github.com/rust-lang/rust/pull/23527#issuecomment-83835448

diff --git a/man/rustc.1 b/man/rustc.1
index 33ef3f9ee4acba4e3078a5a3afb8ac6ccf3849d5..b15829db431dfef89f5d7b6a4fb6217c98874b3b 100644 (file)
--- a/man/rustc.1
+++ b/man/rustc.1
@@ -242,7 +242,7 @@ full debug info with variable and type information.
 \fBopt\-level\fR=\fIVAL\fR
 Optimize with possible levels 0\[en]3
 
-.SH ENVIRONMENT VARIABLES
+.SH ENVIRONMENT
 
 Some of these affect the output of the compiler, while others affect programs
 which link to the standard library.