fix broken link; add trailing slashes

content/elsewhere/adding-a-not-null-column-to-an-existing-table/index.md

@@ -14,7 +14,7 @@ I'll be publishing a series of posts about how to be sure that you're
 taking advantage of all your RDBMS has to offer.*
 
 ASSUMING MY [LAST
-POST](/elsewhere/required-fields-should-be-marked-not-null)
+POST](/elsewhere/required-fields-should-be-marked-not-null/)
 CONVINCED YOU of the *why* of marking required fields `NOT NULL`, the
 next question is *how*. When creating a brand new table, it's
 straightforward enough:

content/elsewhere/functional-programming-in-ruby-with-contracts/index.md

@@ -14,7 +14,7 @@ docs](http://egonschiele.github.io/contracts.ruby/), I couldn't wait to
 try it out. I'd been doing some functional programming as part of our
 ongoing programming challenge series, and saw an opportunity to use
 Contracts to rewrite my Ruby solution to the [One-Time
-Pad](/elsewhere/otp-a-language-agnostic-programming-challenge)
+Pad](/elsewhere/otp-a-language-agnostic-programming-challenge/)
 problem. Check out my [rewritten `encrypt`
 program](https://github.com/vigetlabs/otp/blob/master/languages/Ruby/encrypt):
 

content/elsewhere/otp-a-language-agnostic-programming-challenge/index.md

@@ -86,14 +86,14 @@ languages](https://github.com/vigetlabs/otp/tree/master/languages):
 
 -   [C](https://viget.com/extend/otp-the-fun-and-frustration-of-c)
 -   D
--   [Elixir](/elsewhere/otp-ocaml-haskell-elixir)
+-   [Elixir](/elsewhere/otp-ocaml-haskell-elixir/)
 -   Go
--   [Haskell](/elsewhere/otp-ocaml-haskell-elixir)
+-   [Haskell](/elsewhere/otp-ocaml-haskell-elixir/)
 -   JavaScript 5
 -   JavaScript 6
 -   Julia
 -   [Matlab](https://viget.com/extend/otp-matlab-solution-in-one-or-two-lines)
--   [OCaml](/elsewhere/otp-ocaml-haskell-elixir)
+-   [OCaml](/elsewhere/otp-ocaml-haskell-elixir/)
 -   Ruby
 -   Rust
 -   Swift (thanks [wasnotrice](https://github.com/wasnotrice)!)