doc: fix for the missing links (#5127)

Due to some extension file name "md" missing, the links are invalid.
Here's the fixture for it by putting them together at the last lines.

Refs: #5126

Author: SEWeiTung

pages/en/docs/guides/diagnostics-flamegraph.md

@@ -20,7 +20,7 @@ Flame graphs are generated from `perf` output, which is not a node-specific tool
 
 If you want a single step that produces a flame graph locally, try [0x](https://www.npmjs.com/package/0x)
 
-For diagnosing production deployments, read these notes: [0x production servers](https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md)
+For diagnosing production deployments, read these notes: [0x production servers][].
 
 ### Create a flame graph with system perf tools
 
@@ -122,3 +122,5 @@ it means the Linux perf you're using was not compiled with demangle support, see
 ## Examples
 
 Practice capturing flame graphs yourself with [a flame graph exercise](https://github.com/naugtur/node-example-flamegraph)!
+
+[0x production servers]: https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md

pages/ja/docs/guides/diagnostics-flamegraph.md

@@ -45,7 +45,7 @@ For diagnosing production deployments, read these notes: [0x production servers]
 
 部分的にフレームグラフを作成する単一のステップが必要な場合は、[0x](https://www.npmjs.com/package/0x) を試してください。
 
-運用環境のデプロイメントを診断するために、[0x 運用サーバ](https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md) という注意書きを読みましょう。
+運用環境のデプロイメントを診断するために、[0x 運用サーバ][]という注意書きを読みましょう。
 
 <!--
 ### Create a flame graph with system perf tools
@@ -264,3 +264,5 @@ Practice capturing flame graphs yourself with [a flame graph exercise](https://g
 ## 例
 
 [フレームグラフ演習](https://github.com/naugtur/node-example-flamegraph)を使用してフレームグラフを自分でキャプチャする練習をしてください!
+
+[0x 運用サーバ]: https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md

pages/pt-br/docs/guides/diagnostics-flamegraph.md

@@ -26,7 +26,7 @@ Flame Graphs são gerados a partir da saída do `perf`, que não é uma ferramen
 Se você quiser uma ferramenta simples, de um único passo, que produz um Flame Graph rápido localmente, tente o [0x](https://www.npmjs.com/package/0x)
 
 <!-- For diagnosing production deployments, read these notes: [0x production servers](https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md) -->
-Para diagnosticar problemas em produção, leia estas notas: [0x em servidores de produção](https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md)
+Para diagnosticar problemas em produção, leia estas notas: [0x em servidores de produção][]
 
 ### Criando um Flame Graph com as ferramentas `perf` do sistema
 
@@ -154,3 +154,5 @@ Significa que a versão do perf que voc6e está usando no Linux não foi compila
 
 <!-- Practice capturing flame graphs yourself with [a flame graph exercise](https://github.com/naugtur/node-example-flamegraph)! -->
 Pratique capturando amostras e gerando flame graphs você mesmo com [este exercício](https://github.com/naugtur/node-example-flamegraph)!
+
+[0x em servidores de produção]: https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md

pages/zh-cn/docs/guides/diagnostics-flamegraph.md

@@ -19,7 +19,7 @@ layout: docs.hbs
 
 如果你想在本地开始单一输出火焰图，请尝试 [0x](https://www.npmjs.com/package/0x)
 
-如果你想诊断发布的生产环境，请阅读[在生产环境中的 0x](https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md)
+如果你想诊断发布的生产环境，请阅读[在生产环境中的 0x][]。
 
 ### <!--create-a-flame-graph-with-system-perf-tools-->用系统工具 `pref` 创建火焰图
 
@@ -119,3 +119,5 @@ node`_ZN2v88internal11interpreter17BytecodeGenerator15VisitStatementsEPNS0_8Zone
 ## 示例部分
 
 请通过[火焰图练习](https://github.com/naugtur/node-example-flamegraph)来练习捕获你的火焰图吧！
+
+[在生产环境中的 0x]: https://github.com/davidmarkclements/0x/blob/master/docs/production-servers.md