docs(env variables): small wording change (can => have to)

[vvo]

When reading
"In order to expose a variable to the browser you can prefix the variable with NEXT_PUBLIC_. For example:"

I thought that I could maybe use something else than NEXT_PUBLIC_. I guess "have to" or similar would be better here, let me know

[ijjk]

Stats from current PR

Default Server Mode (Decrease detected ✓)

General

	vercel/next.js canary	vvo/next.js patch-1	Change
buildDuration	10.6s	11.1s	⚠️ +424ms
nodeModulesSize	66 MB	66 MB	✓

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vvo/next.js patch-1	Change
/ failed reqs	0	0	✓
/ total time (seconds)	1.914	1.902	-0.01
/ avg req/sec	1305.97	1314.64	⚠️ +8.67
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.205	1.295	⚠️ +0.09
/error-in-render avg req/sec	2074.52	1930.19	-144.33

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vvo/next.js patch-1	Change
main-HASH.js gzip	6.59 kB	6.59 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..6c2a.js gzip	10.5 kB	10.5 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	57 kB	57 kB	✓

Client Bundles (main, webpack, commons) Modern

	vercel/next.js canary	vvo/next.js patch-1	Change
main-HASH.module.js gzip	5.67 kB	5.67 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.93 kB	6.93 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	52.5 kB	52.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vvo/next.js patch-1	Change
polyfills-HASH.js gzip	26.3 kB	26.3 kB	✓
Overall change	26.3 kB	26.3 kB	✓

Client Pages

	vercel/next.js canary	vvo/next.js patch-1	Change
_app.js gzip	1.26 kB	1.26 kB	✓
_error.js gzip	3.25 kB	3.25 kB	✓
hooks.js gzip	881 B	881 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	2.05 kB	2.05 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	8.21 kB	8.21 kB	✓

Client Pages Modern

	vercel/next.js canary	vvo/next.js patch-1	Change
_app.module.js gzip	604 B	604 B	✓
_error.module.js gzip	2.04 kB	2.04 kB	✓
hooks.module.js gzip	383 B	383 B	✓
index.module.js gzip	223 B	223 B	✓
link.module.js gzip	1.51 kB	1.51 kB	✓
routerDirect..dule.js gzip	281 B	281 B	✓
withRouter.m..dule.js gzip	278 B	278 B	✓
Overall change	5.32 kB	5.32 kB	✓

Client Build Manifests

	vercel/next.js canary	vvo/next.js patch-1	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

	vercel/next.js canary	vvo/next.js patch-1	Change
index.html gzip	924 B	924 B	✓
link.html gzip	934 B	934 B	✓
withRouter.html gzip	922 B	922 B	✓
Overall change	2.78 kB	2.78 kB	✓

---

Serverless Mode

General

	vercel/next.js canary	vvo/next.js patch-1	Change
buildDuration	11.5s	11.3s	-219ms
nodeModulesSize	66 MB	66 MB	✓

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vvo/next.js patch-1	Change
main-HASH.js gzip	6.59 kB	6.59 kB	✓
webpack-HASH.js gzip	746 B	746 B	✓
de003c3a9d30..6c2a.js gzip	10.5 kB	10.5 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	57 kB	57 kB	✓

Client Bundles (main, webpack, commons) Modern

	vercel/next.js canary	vvo/next.js patch-1	Change
main-HASH.module.js gzip	5.67 kB	5.67 kB	✓
webpack-HASH..dule.js gzip	746 B	746 B	✓
de003c3a9d30..dule.js gzip	6.93 kB	6.93 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	52.5 kB	52.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vvo/next.js patch-1	Change
polyfills-HASH.js gzip	26.3 kB	26.3 kB	✓
Overall change	26.3 kB	26.3 kB	✓

Client Pages

	vercel/next.js canary	vvo/next.js patch-1	Change
_app.js gzip	1.26 kB	1.26 kB	✓
_error.js gzip	3.25 kB	3.25 kB	✓
hooks.js gzip	881 B	881 B	✓
index.js gzip	222 B	222 B	✓
link.js gzip	2.05 kB	2.05 kB	✓
routerDirect.js gzip	279 B	279 B	✓
withRouter.js gzip	278 B	278 B	✓
Overall change	8.21 kB	8.21 kB	✓

Client Pages Modern

	vercel/next.js canary	vvo/next.js patch-1	Change
_app.module.js gzip	604 B	604 B	✓
_error.module.js gzip	2.04 kB	2.04 kB	✓
hooks.module.js gzip	383 B	383 B	✓
index.module.js gzip	223 B	223 B	✓
link.module.js gzip	1.51 kB	1.51 kB	✓
routerDirect..dule.js gzip	281 B	281 B	✓
withRouter.m..dule.js gzip	278 B	278 B	✓
Overall change	5.32 kB	5.32 kB	✓

Client Build Manifests

	vercel/next.js canary	vvo/next.js patch-1	Change
_buildManifest.js gzip	61 B	61 B	✓
_buildManife..dule.js gzip	61 B	61 B	✓
Overall change	122 B	122 B	✓

Serverless bundles

	vercel/next.js canary	vvo/next.js patch-1	Change
_error.js	878 kB	878 kB	✓
404.html	4.18 kB	4.18 kB	✓
hooks.html	3.81 kB	3.81 kB	✓
index.js	879 kB	879 kB	✓
link.js	916 kB	916 kB	✓
routerDirect.js	909 kB	909 kB	✓
withRouter.js	909 kB	909 kB	✓
Overall change	4.5 MB	4.5 MB	✓

[timneutkens]

Sounds good 👍