docs: Fix spelling error.

Spotted by Nikola Smiljanic.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171407 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/Tooling.rst b/docs/Tooling.rst
index b1281fc..190fb5c 100644
--- a/docs/Tooling.rst
+++ b/docs/Tooling.rst
@@ -72,7 +72,7 @@
 * want to run tools over a single file, or a specific subset of files,
   independently of the build system
 * want full control over the Clang AST
-* want to share code with Clang Plgins
+* want to share code with Clang Plugins
 
 Do not use LibTooling when you...: