doc: add Temporal section to Table of Contents

Move the "Building Node.js with Temporal support" section in
`BUILDING.md` so that it is not in the middle of the OpenSSL sections
and add it to the Table of Contents.

PR-URL: #61805
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: richardlau

BUILDING.md

@@ -57,6 +57,7 @@ file a new issue.
     * [Windows](#windows-4)
 * [Configuring OpenSSL config appname](#configure-openssl-appname)
 * [Building Node.js with FIPS-compliant OpenSSL](#building-nodejs-with-fips-compliant-openssl)
+* [Building Node.js with Temporal support](#building-nodejs-with-temporal-support)
 * [Building Node.js with external core modules](#building-nodejs-with-external-core-modules)
   * [Unix/macOS](#unixmacos-4)
   * [Windows](#windows-5)
@@ -1027,6 +1028,15 @@ configure option:
 ./configure --openssl-conf-name=<some_conf_name>
 ```
 
+## Building Node.js with FIPS-compliant OpenSSL
+
+Node.js supports FIPS when statically or dynamically linked with OpenSSL 3 via
+[OpenSSL's provider model](https://docs.openssl.org/3.0/man7/crypto/#OPENSSL-PROVIDERS).
+It is not necessary to rebuild Node.js to enable support for FIPS.
+
+See [FIPS mode](doc/api/crypto.md#fips-mode) for more information on how to
+enable FIPS support in Node.js.
+
 ## Building Node.js with Temporal support
 
 Node.js supports the [Temporal](https://github.com/tc39/proposal-temporal) APIs, when
@@ -1037,15 +1047,6 @@ To build Node.js with Temporal support, a Rust toolchain is required:
 * rustc >= 1.82 (with LLVM >= 19)
 * cargo >= 1.82
 
-## Building Node.js with FIPS-compliant OpenSSL
-
-Node.js supports FIPS when statically or dynamically linked with OpenSSL 3 via
-[OpenSSL's provider model](https://docs.openssl.org/3.0/man7/crypto/#OPENSSL-PROVIDERS).
-It is not necessary to rebuild Node.js to enable support for FIPS.
-
-See [FIPS mode](doc/api/crypto.md#fips-mode) for more information on how to
-enable FIPS support in Node.js.
-
 ## Building Node.js with external core modules
 
 It is possible to specify one or more JavaScript text files to be bundled in