Ignore some URLs that don't seem to work with htmlproofer

.ci/url_ignore

@@ -0,0 +1,3 @@
+https://amzn.com/B00QRRZ2QM
+https://blogs.oracle.com/linux/strace-the-sysadmins-microscope-v2
+https://tiswww.case.edu/php/chet/readline/rltop.html

.travis.yml

@@ -5,4 +5,12 @@ before_script:
   - gem install html-proofer
 script:
   - bundle exec jekyll build
-  - htmlproofer --check-html --check-favicon ./_site
+  - >-
+    htmlproofer ./_site
+    --check-html
+    --check-favicon
+    --check-external-hash
+    --check-img-http
+    --check-opengraph
+    --empty-alt-ignore
+    --url-ignore $(paste -sd ',' < .ci/url_ignore)

_2019/security.md

@@ -46,7 +46,7 @@ also has a good blog post on [travel security
 advice](https://medium.com/@thegrugq/stop-fabricating-travel-security-advice-35259bf0e869)
 that's worth reading. We'll repeat much of the advice from those sources
 here, plus some more. Also, get a [USB data
-blocker](https://www.amazon.com/dp/B00QRRZ2QM), because [USB is
+blocker](https://amzn.com/B00QRRZ2QM), because [USB is
 scary](https://www.bleepingcomputer.com/news/security/heres-a-list-of-29-different-types-of-usb-attacks/).
 
 ## Authentication