Add translation key

Author: corwintines

src/intl/en/page-developers-docs.json

@@ -33,6 +33,7 @@
   "docs-nav-development-networks-description": "Local blockchain environments used to test dapps before deployment",
   "docs-nav-dex-design-best-practice": "Decentralized Exchange (DEX) design best practices",
   "docs-nav-dot-net": ".NET",
+  "docs-nav-elixir": "Elixir",
   "docs-nav-erc-20": "ERC-20: Fungible Tokens",
   "docs-nav-erc-721": "ERC-721: NFTs",
   "docs-nav-erc-777": "ERC-777",