doc: fix capitalization of ASan

PR-URL: nodejs#47676
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>

BUILDING.md

@@ -29,7 +29,7 @@ file a new issue.
     * [Running Coverage](#running-coverage)
     * [Building the documentation](#building-the-documentation)
     * [Building a debug build](#building-a-debug-build)
-    * [Building an ASAN build](#building-an-asan-build)
+    * [Building an ASan build](#building-an-asan-build)
     * [Speeding up frequent rebuilds when developing](#speeding-up-frequent-rebuilds-when-developing)
     * [Troubleshooting Unix and macOS builds](#troubleshooting-unix-and-macos-builds)
   * [Windows](#windows)
@@ -502,16 +502,16 @@ $ gdb /opt/node-debug/node core.node.8.1535359906
 $ backtrace
 ```
 
-#### Building an ASAN build
+#### Building an ASan build
 
-[ASAN](https://github.com/google/sanitizers) can help detect various memory
-related bugs. ASAN builds are currently only supported on linux.
+[ASan](https://github.com/google/sanitizers) can help detect various memory
+related bugs. ASan builds are currently only supported on linux.
 If you want to check it on Windows or macOS or you want a consistent toolchain
 on Linux, you can try [Docker](https://www.docker.com/products/docker-desktop)
 (using an image like `gengjiawen/node-build:2020-02-14`).
 
 The `--debug` is not necessary and will slow down build and testing, but it can
-show clear stacktrace if ASAN hits an issue.
+show clear stacktrace if ASan hits an issue.
 
 ```console
 $  ./configure --debug --enable-asan && make -j4