chore(misc): update .gitignore help link (#30051)

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## Current Behavior
Currently when we generate a `.gitignore` file we include a help link to
http://help.github.com/ignore-files/ which is no longer a valid url.

## Expected Behavior
It should link to the new help link
https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files

## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->

Fixes #29794

packages/nuxt/src/utils/__snapshots__/update-gitignore.spec.ts.snap

@@ -2,7 +2,7 @@
 
 exports[`update gitignore should add entries to .gitignore if they do not exist 1`] = `
 "
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist
@@ -32,7 +32,7 @@ node_modules
 
 exports[`update gitignore should not add duplicate entries to .gitignore if they already exist 1`] = `
 "
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist

packages/nuxt/src/utils/update-gitignore.spec.ts

@@ -13,7 +13,7 @@ describe('update gitignore', () => {
     tree.write(
       '.gitignore',
       `
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist
@@ -44,7 +44,7 @@ node_modules
     tree.write(
       '.gitignore',
       `
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist

packages/workspace/src/generators/new/files-integrated-repo/__dot__gitignore

@@ -1,4 +1,4 @@
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist

packages/workspace/src/generators/new/files-package-based-repo/__dot__gitignore

@@ -1,4 +1,4 @@
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist

packages/workspace/src/generators/new/files-root-app/__dot__gitignore

@@ -1,4 +1,4 @@
-# See http://help.github.com/ignore-files/ for more about ignoring files.
+# See https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files for more about ignoring files.
 
 # compiled output
 dist