Update docsy to 0.7.1

[chalin]

The Docsy patch release mainly fixes blog index page layout issues:

$ (cd public && git diff -bw --ignore-blank-lines -- . ':(exclude)*.xml') | grep ^diff | grep -v \.css                        
diff --git a/blog/index.html b/blog/index.html
diff --git a/blog/page/2/index.html b/blog/page/2/index.html
diff --git a/blog/page/3/index.html b/blog/page/3/index.html
diff --git a/blog/page/4/index.html b/blog/page/4/index.html
diff --git a/blog/page/5/index.html b/blog/page/5/index.html
diff --git a/blog/page/6/index.html b/blog/page/6/index.html
diff --git a/blog/page/7/index.html b/blog/page/7/index.html
diff --git a/blog/page/8/index.html b/blog/page/8/index.html