[Docs] Update heading

[lfades]

This is causing issues with the Algolia indexing of this page. Currently every documentation page has to have a top level 1 heading.

[ijjk]

Stats from current PR

Default Server Mode (Decrease detected ✓)

General

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
buildDuration	10.5s	10.4s	-6ms
nodeModulesSize	58.3 MB	58.3 MB	✓

Page Load Tests Overall decrease ⚠️

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
/ failed reqs	0	0	✓
/ total time (seconds)	1.815	1.743	-0.07
/ avg req/sec	1377.36	1434.35	⚠️ +56.99
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	0.991	1.033	⚠️ +0.04
/error-in-render avg req/sec	2523.84	2418.98	-104.86

Client Bundles (main, webpack, commons)

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
main-HASH.js gzip	6.68 kB	6.68 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..e49d.js gzip	10.4 kB	10.4 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	57 kB	57 kB	✓

Client Bundles (main, webpack, commons) Modern

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
main-HASH.module.js gzip	5.72 kB	5.72 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.85 kB	6.85 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	52.5 kB	52.5 kB	✓

Legacy Client Bundles (polyfills)

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
polyfills-HASH.js gzip	26.3 kB	26.3 kB	✓
Overall change	26.3 kB	26.3 kB	✓

Client Pages

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_app.js gzip	1.26 kB	1.26 kB	✓
_error.js gzip	3.28 kB	3.28 kB	✓
hooks.js gzip	881 B	881 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	2.06 kB	2.06 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	8.26 kB	8.26 kB	✓

Client Pages Modern

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_app.module.js gzip	604 B	604 B	✓
_error.module.js gzip	2.09 kB	2.09 kB	✓
hooks.module.js gzip	383 B	383 B	✓
index.module.js gzip	223 B	223 B	✓
link.module.js gzip	1.52 kB	1.52 kB	✓
routerDirect..dule.js gzip	281 B	281 B	✓
withRouter.m..dule.js gzip	278 B	278 B	✓
Overall change	5.38 kB	5.38 kB	✓

Client Build Manifests

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_buildManifest.js gzip	61 B	61 B	✓
_buildManife..dule.js gzip	61 B	61 B	✓
Overall change	122 B	122 B	✓

Rendered Page Sizes

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
index.html gzip	925 B	925 B	✓
link.html gzip	936 B	936 B	✓
withRouter.html gzip	922 B	922 B	✓
Overall change	2.78 kB	2.78 kB	✓

---

Serverless Mode

General

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
buildDuration	12s	11.8s	-154ms
nodeModulesSize	58.3 MB	58.3 MB	✓

Client Bundles (main, webpack, commons)

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
main-HASH.js gzip	6.68 kB	6.68 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..e49d.js gzip	10.4 kB	10.4 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	57 kB	57 kB	✓

Client Bundles (main, webpack, commons) Modern

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
main-HASH.module.js gzip	5.72 kB	5.72 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.85 kB	6.85 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	52.5 kB	52.5 kB	✓

Legacy Client Bundles (polyfills)

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
polyfills-HASH.js gzip	26.3 kB	26.3 kB	✓
Overall change	26.3 kB	26.3 kB	✓

Client Pages

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_app.js gzip	1.26 kB	1.26 kB	✓
_error.js gzip	3.28 kB	3.28 kB	✓
hooks.js gzip	881 B	881 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	2.06 kB	2.06 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	8.26 kB	8.26 kB	✓

Client Pages Modern

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_app.module.js gzip	604 B	604 B	✓
_error.module.js gzip	2.09 kB	2.09 kB	✓
hooks.module.js gzip	383 B	383 B	✓
index.module.js gzip	223 B	223 B	✓
link.module.js gzip	1.52 kB	1.52 kB	✓
routerDirect..dule.js gzip	281 B	281 B	✓
withRouter.m..dule.js gzip	278 B	278 B	✓
Overall change	5.38 kB	5.38 kB	✓

Client Build Manifests

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_buildManifest.js gzip	61 B	61 B	✓
_buildManife..dule.js gzip	61 B	61 B	✓
Overall change	122 B	122 B	✓

Serverless bundles

	zeit/next.js canary	lfades/next.js fix/docs-subtitle	Change
_error.js	850 kB	850 kB	✓
404.html	4.18 kB	4.18 kB	✓
hooks.html	3.81 kB	3.81 kB	✓
index.js	851 kB	851 kB	✓
link.js	888 kB	888 kB	✓
routerDirect.js	880 kB	880 kB	✓
withRouter.js	880 kB	880 kB	✓
Overall change	4.36 MB	4.36 MB	✓