Added link to the PL/SQL language server (#2057)

Author: EwanDubashinski

_implementors/servers.md

@@ -174,6 +174,7 @@ index: 1
 | PHP | [Dan Leech](https://github.com/dantleech) | [phpactor](https://github.com/phpactor/phpactor) | PHP |
 | PHPUnit | [Recca0120](https://github.com/recca0120) | [phpunit-language-server](https://github.com/recca0120/vscode-phpunit) | TypeScript |
 | [IBM Enterprise **PL/I** for z/OS](https://www.ibm.com/support/knowledgecenter/SSY2V3_5.3.0/com.ibm.ent.pl1.zos.doc/single_template_nobrand.html) | IBM |  [IBM Z Open Editor VS Code extension](https://marketplace.visualstudio.com/items?itemName=IBM.zopeneditor) | Java |
+| PL/SQL | [Ivan Dubashinskii](https://github.com/EwanDubashinski) | [PL/SQL language server](https://github.com/EwanDubashinski/plsqllang-server) | Java |
 | [Polymer](https://www.polymer-project.org) | [Polymer Team](https://github.com/Polymer) | [polymer-editor-service](https://github.com/Polymer/polymer-editor-service) | TypeScript |
 | PowerPC Assembly | [Noah Fields](https://github.com/OGoodness) | [PowerPC Support](https://github.com/OGoodness/VSCode-PowerPC-Syntax) | TypeScript |
 | PowerShell | MS | [PowerShell Editor Services](https://github.com/PowerShell/PowerShellEditorServices) | C# |