make sure that environment-variables page is built

PR 1845 seems to have forgotten to add the page to the DOCS variable in
the makefile

diff --git a/Makefile.in b/Makefile.in
index f6d8c99783173478d0a9df3ce4762cc5ac9f7842..0dd5c2c88a14813bb63f501de716fd60eb330dfc 100644 (file)
--- a/Makefile.in
+++ b/Makefile.in
@@ -119,7 +119,8 @@ clean:
 
 # === Documentation
 
-DOCS := index faq config guide manifest build-script pkgid-spec crates-io
+DOCS := index faq config guide manifest build-script pkgid-spec crates-io \
+       environment-variables
 DOC_DIR := target/doc
 DOC_OPTS := --markdown-no-toc \
                --markdown-css stylesheets/normalize.css \