docs: suggest cloning with depth=1 to avoid huge downloads

[gsimone]

Lifted the good idea from three.js, where the total download size is a comparable 2GB.

[ijjk]

Thanks!

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General

	vercel/next.js canary	gsimone/next.js patch-1	Change
buildDuration	15.1s	15s	-94ms
buildDurationCached	6s	6s	-94ms
nodeModulesSize	484 MB	484 MB	✓

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	gsimone/next.js patch-1	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.957	3.003	⚠️ +0.05
/ avg req/sec	845.5	832.42	⚠️ -13.08
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.133	1.164	⚠️ +0.03
/error-in-render avg req/sec	2205.78	2148.48	⚠️ -57.3

Client Bundles (main, webpack)

	vercel/next.js canary	gsimone/next.js patch-1	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	28 kB	28 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.7 kB	71.7 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	gsimone/next.js patch-1	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	gsimone/next.js patch-1	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	192 B	192 B	✓
amp-HASH.js gzip	309 B	309 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	3.05 kB	3.05 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.68 kB	5.68 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.32 kB	2.32 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	15.9 kB	15.9 kB	✓

Client Build Manifests

	vercel/next.js canary	gsimone/next.js patch-1	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	gsimone/next.js patch-1	Change
index.html gzip	531 B	531 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General

	vercel/next.js canary	gsimone/next.js patch-1	Change
buildDuration	17.9s	18.2s	⚠️ +351ms
buildDurationCached	6s	6s	⚠️ +31ms
nodeModulesSize	484 MB	484 MB	✓

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	gsimone/next.js patch-1	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.021	3.04	⚠️ +0.02
/ avg req/sec	827.62	822.47	⚠️ -5.15
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.153	1.151	0
/error-in-render avg req/sec	2167.62	2172.26	+4.64

Client Bundles (main, webpack)

	vercel/next.js canary	gsimone/next.js patch-1	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.3 kB	28.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.3 kB	72.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	gsimone/next.js patch-1	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	gsimone/next.js patch-1	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	313 B	313 B	✓
css-HASH.js gzip	325 B	325 B	✓
dynamic-HASH.js gzip	3.03 kB	3.03 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.74 kB	5.74 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.38 kB	2.38 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	388 B	388 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	16 kB	16 kB	✓

Client Build Manifests

	vercel/next.js canary	gsimone/next.js patch-1	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	gsimone/next.js patch-1	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 52b4214