add slugs, fix tables

content/books/_index.md

@@ -1,5 +1,6 @@
 ---
 title: Books
+slug: books
 ---
 
 Here you can record books that you read.

content/books/current/_index.md

@@ -1,6 +1,7 @@
 ---
 title: Currently Reading
 weight: 4
+slug: current
 ---
 
 Here you can record books that you are currently reading.

content/books/log/_index.md

@@ -1,6 +1,7 @@
 ---
 title: Read
 weight: 2
+slug: log
 ---
 
 Here you can record books that you have previously read.

content/books/wishlist/_index.md

@@ -1,6 +1,7 @@
 ---
 title: To-Read
 weight: 3
+slug: wishlist
 ---
 
 Here you can record books that you would like to read.