fix: update links in DOCS

[junha-ahn]

Motivation

Update broken links in the Document

Description

1. There is no CLI document in the docs/pages so Removed a line
2. And Update two links (CONTRIBUTING, SECURITY)

Steps to test or reproduce

No test Here.

[CLAassistant]

All committers have signed the CLA.

[matthewkeil]

Thank you very much for the submission!! We actually just updated our docs a couple weeks ago and noticed the broken links. They are updated here and I have used this PR as an opportunity to test our new workflow to deploy those changes. Thank you again for your contribution.

Please see the notes below.

1. There is no CLI document in the docs/pages so Removed a line

The page that link points to is generated at docs build time.

lodestar/packages/cli/docsgen/index.ts

Line 24 in c86a669

fs.writeFileSync(path.join(folder, `${cmd.command}-cli.md`), docstring);

2. And Update two links (CONTRIBUTING, SECURITY)

Those two pages are moved in from the root of the repo to be included with the docs at build time.

lodestar/scripts/prepare-docs.sh

Line 10 in c86a669

cp CONTRIBUTING.md $DOCS_DIR/pages/contribution/getting-started.md

Because these changes are not needed I am going to close this PR but please feel free to submit anything else you find as our docs are fresh off a full rewrite and there may still be some errors in there.