Change SSH key generation instructions to use the Ed25519 algorithm

[keremgocen]

Why:

Complements the work done for #362 by editing the related pages to change SSH key generation instructions to use the Ed25519 algorithm.

What's being changed:

The following pages are updated with Ed25519 changes suggested in #876

• "Monitoring cluster nodes"
• "Creating a pre-receive hook script"

Check off the following:

• All of the tests are passing.
• I have reviewed my changes in staging.
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

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[keremgocen]

Actually some local tests are failing but I don't think they are related, same tests are failing on the main branch as well.
My node version is v12.18.3

 FAIL  tests/rendering/server.js (29.706 s)
  ● static assets › fonts

    expect(received).toBe(expected) // Object.is equality

    Expected: 200
    Received: 404

      565 | describe('static assets', () => {
      566 |   test('fonts', async () => {
    > 567 |     expect((await get('/dist/fonts/Inter-Medium.woff')).statusCode).toBe(200)
          |                                                                     ^
      568 |     expect((await get('/dist/fonts/Inter-Regular.woff')).statusCode).toBe(200)
      569 |   })
      570 | })

      at Object.<anonymous> (tests/rendering/server.js:567:69)
          at runMicrotasks (<anonymous>)

  ● stylesheets › compiles and sets the right content-type header

    expect(received).toBe(expected) // Object.is equality

    Expected: 200
    Received: 404

      663 |   it('compiles and sets the right content-type header', async () => {
      664 |     const res = await get('/dist/index.css')
    > 665 |     expect(res.statusCode).toBe(200)
          |                            ^
      666 |     expect(res.headers['content-type']).toBe('text/css; charset=UTF-8')
      667 |   })
      668 | })

      at Object.<anonymous> (tests/rendering/server.js:665:28)
          at runMicrotasks (<anonymous>)

  ● client-side JavaScript bundle › returns a 200 response

    expect(received).toBe(expected) // Object.is equality

    Expected: 200
    Received: 404

      676 |
      677 |   it('returns a 200 response', async () => {
    > 678 |     expect(res.statusCode).toBe(200)
          |                            ^
      679 |   })
      680 |
      681 |   it('sets the right content-type header', async () => {

      at Object.<anonymous> (tests/rendering/server.js:678:28)
          at runMicrotasks (<anonymous>)

  ● client-side JavaScript bundle › sets the right content-type header

    expect(received).toBe(expected) // Object.is equality

    Expected: "application/javascript; charset=UTF-8"
    Received: "text/html; charset=utf-8"

      680 |
      681 |   it('sets the right content-type header', async () => {
    > 682 |     expect(res.headers['content-type']).toBe('application/javascript; charset=UTF-8')          |                                         ^
      683 |   })
      684 |
      685 |   // TODO: configure webpack to create production bundle in the test env

      at Object.<anonymous> (tests/rendering/server.js:682:41)
          at runMicrotasks (<anonymous>)

 FAIL  tests/javascripts/user-agent.js
  ● Test suite failed to run

    Jest encountered an unexpected token

    This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.

    By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".

[sarahs]

👋 @keremgocen I think running npm run build locally should fix those errors. This is a one-time step to create static assets.

I thought we had internal documentation about this but couldn't find it, so I opened #984 to add this info.

[hubwriter]

@keremgocen - The changes you've made all look good. 👍
Many thanks for contributing. 🎖️

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours.