Add "md-nits" make target

Also fix a nit in recent CHANGES.md update.
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/11770)

.travis.yml

@@ -205,10 +205,14 @@ script:
           travis_terminate 1;
       fi
     - if test -n "$MARKDOWNLINT" ; then
-          echo -e "====START MARKDOWNLINT====";
-          gem install mdl || travis_terminate 1;
-          mdl -s util/markdownlint.rb . || travis_terminate 1;
-          echo -e "====END MARKDOWNLINT====";
+          if ! gem install mdl ; then
+              echo -e '\052\052 FAILED -- GEM INSTALL MDL';
+              travis_terminate 1;
+          fi;
+          if ! $make md-nits ; then
+              echo -e '\052\052 FAILED -- MAKE MD-NITS';
+              travis_terminate 1;
+          fi;
       fi
     - if ! $make2; then
           echo -e '\052\052 FAILED -- MAKE';

Configurations/unix-Makefile.tmpl

@@ -519,7 +519,7 @@ clean: libclean
 	-$(RM) `find . -name '*{- platform->depext() -}' \! -name '.*' \! -type d -print`
 	-$(RM) `find . -name '*{- platform->objext() -}' \! -name '.*' \! -type d -print`
 	$(RM) core
-	$(RM) tags TAGS doc-nits cmd-nits
+	$(RM) tags TAGS doc-nits cmd-nits md-nits
 	$(RM) -r test/test-runs
 	$(RM) openssl.pc libcrypto.pc libssl.pc
 	-$(RM) `find . -type l \! -name '.*' -print`
@@ -982,13 +982,22 @@ update: generate errors ordinals
 generate: generate_apps generate_crypto_bn generate_crypto_objects \
           generate_crypto_conf generate_crypto_asn1 generate_fuzz_oids
 
-.PHONY: doc-nits cmd-nits
+.PHONY: doc-nits cmd-nits md-nits
 doc-nits: build_generated
 	$(PERL) $(SRCDIR)/util/find-doc-nits -n -l -e
 
 cmd-nits: build_generated apps/openssl
 	$(PERL) $(SRCDIR)/util/find-doc-nits -c
 
+# This uses "mdl", the markdownlint application, which is written in ruby.
+# The source is at https://github.com/markdownlint/markdownlint
+# If you have ruby installed, "gem install mdl" should work.
+# Another option is at https://snapcraft.io/install/mdl/debian
+# Finally, there's a Node.js version, which we haven't tried, that
+# can be found at https://github.com/DavidAnson/markdownlint
+md-nits:
+	mdl -s util/markdownlint.rb .
+
 # Test coverage is a good idea for the future
 #coverage: $(PROGRAMS) $(TESTPROGRAMS)
 #	...