doc: get Suricata version from autoconf vars

doc/userguide/Makefile.am

@@ -4,11 +4,13 @@ man1_MANS = _build/man/suricata.1
 html:
 	sysconfdir=$(sysconfdir) \
 	localstatedir=$(localstatedir) \
+	version=$(PACKAGE_VERSION) \
 		sphinx-build -b html -d _build/doctrees . _build/html
 
 _build/man/suricata.1:
 	sysconfdir=$(sysconfdir) \
 	localstatedir=$(localstatedir) \
+	version=$(PACKAGE_VERSION) \
 		sphinx-build -b man -d _build/doctrees . _build/man
 
 clean-local:

doc/userguide/conf.py

@@ -57,7 +57,7 @@ author = u'OISF'
 # built documents.
 #
 # The short X.Y version.
-version = '3.0dev'
+version = os.environ.get('version', "unknown")
 # The full version, including alpha/beta/rc tags.
 release = version