Fix gh action workflow when docs changed

[styfle]

Fixes this issue: https://github.com/vercel/next.js/pull/28077/checks?check_run_id=3326281106

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
buildDuration	11.6s	11.5s	-120ms
buildDurationCached	3s	2.9s	-71ms
nodeModulesSize	49.1 MB	49.1 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.313	2.314	0
/ avg req/sec	1080.76	1080.44	⚠️ -0.32
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.264	1.241	-0.02
/error-in-render avg req/sec	1978.21	2015.05	+36.84

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
745.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	23.1 kB	23.1 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	67 kB	67 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
_app-HASH.js gzip	980 B	980 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.64 kB	2.64 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	904 B	904 B	✓
image-HASH.js gzip	4.13 kB	4.13 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	319 B	319 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	12.9 kB	12.9 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
_buildManifest.js gzip	491 B	491 B	✓
Overall change	491 B	491 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
index.html gzip	539 B	539 B	✓
link.html gzip	551 B	551 B	✓
withRouter.html gzip	532 B	532 B	✓
Overall change	1.62 kB	1.62 kB	✓

---

Webpack 4 Mode (Increase detected ⚠️)

General

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
buildDuration	9.4s	9.4s	-40ms
buildDurationCached	3.9s	3.9s	-47ms
nodeModulesSize	49.1 MB	49.1 MB	✓

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.336	2.271	-0.06
/ avg req/sec	1070.09	1100.87	+30.78
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.326	1.271	-0.06
/error-in-render avg req/sec	1885.57	1966.99	+81.42

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
16.HASH.js gzip	186 B	186 B	✓
677f882d2ed8..HASH.js gzip	14 kB	14 kB	✓
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	10.6 kB	10.6 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	67.9 kB	67.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
_app-HASH.js gzip	965 B	965 B	✓
_error-HASH.js gzip	3.71 kB	3.71 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.83 kB	2.83 kB	✓
head-HASH.js gzip	2.97 kB	2.97 kB	✓
hooks-HASH.js gzip	911 B	911 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	2.95 kB	2.95 kB	✓
withRouter-HASH.js gzip	294 B	294 B	✓
e025d2764813..52f.css gzip	125 B	125 B	✓
Overall change	17.8 kB	17.8 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
_buildManifest.js gzip	497 B	497 B	✓
Overall change	497 B	497 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js fix-docs-only-run	Change
index.html gzip	584 B	584 B	✓
link.html gzip	596 B	596 B	✓
withRouter.html gzip	577 B	577 B	✓
Overall change	1.76 kB	1.76 kB	✓

Commit: b1fd56b