luci-app-example: Fix typo in README.md /s/id/is/

[cpswan]

• This PR is not from my main or master branch 💩, but a separate branch ✅
• Each commit has a valid ✒️ Signed-off-by: <my@email.address> row (via git commit --signoff)
• Each commit and PR title has a valid 📝 <package name>: title first line subject for packages
• Incremented 🆙 any PKG_VERSION in the Makefile NA
• Tested on: (architecture, openwrt version, browser) ✅ NA
• ( Preferred ) Mention: @ the original code author for feedback @stokito
• ( Preferred ) Screenshot or mp4 of changes:
• ( Optional ) Closes: e.g. openwrt/luci#issue-number
• ( Optional ) Depends on: e.g. openwrt/packages#pr-number in sister repo
• Description: Fix a minor typo I spotted whilst learning from the example application.

[cpswan]

I see that Test Formalities is failing with:

: Signed-off-by is missing or doesn't match author (should be 'Signed-off-by: Chris Swan <478926+cpswan@users.noreply.github.com>')
: Real email address policy: please configure GitHub email (<478926+cpswan@users.noreply.github.com>) to a real one

But that seems at odds with the statement in the PR template:

MAY:
- your S.O.B. *may* be a nickname

So I'm hoping that I don't have to reconfigure my GitHub profile setting just to keep the bot happy.

[stokito]

Chris Swan <@cpswan> looks like an email. You may use private email https://docs.github.com/en/account-and-profile/setting-up-and-managing-your-personal-account-on-github/managing-email-preferences/setting-your-commit-email-address

[cpswan]

Thanks @stokito I've amended the commit to my usual GitHub email. I think the check will still fail, but I hope that's what you were asking for.