Make Travis docs build more lenient (#16)

diff --git a/.travis.yml b/.travis.yml
index 140a890..1066e5f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -33,7 +33,7 @@
         - cd Doc
         - make venv PYTHON=python3
       script:
-        - make html SPHINXBUILD="./venv/bin/python3 -m sphinx" SPHINXOPTS="-n -q -b linkcheck"
+        - make html SPHINXBUILD="./venv/bin/python3 -m sphinx" SPHINXOPTS="-q"
     - os: linux
       language: c
       compiler: clang