Document Fleet as a Go module workaround and remove Go module publishing workflow (#48773)

.github/workflows/publish-go-module.yml

@@ -1,44 +0,0 @@
-# Workflow to publish Fleet's go module github.com/fleetdm/fleet/v4 on every release.
-# It follows the instructions defined in https://go.dev/doc/modules/publishing.
-#
-# The workflow will be triggered when tagging v4.XX.YY
-# (which is performed on every release).
-name: Publish go module
-
-on:
-  push:
-    tags:
-      - "v4.*"
-
-defaults:
-  run:
-    # fail-fast using bash -eo pipefail. See https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#exit-codes-and-error-action-preference
-    shell: bash
-
-permissions:
-  contents: read
-
-jobs:
-  publish-go-module-list:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Harden Runner
-        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
-        with:
-          egress-policy: audit
-
-      - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
-        with:
-          persist-credentials: false
-
-      - name: Install Go
-        uses: actions/setup-go@4b73464bb391d4059bd26b0524d20df3927bd417 # v6.3.0
-        with:
-          go-version-file: 'go.mod'
-          # Security best practice to disable caching in release/publish workflows
-          cache: false
-
-      - name: Publish go module
-        run: |
-          GOPROXY=proxy.golang.org go list -m github.com/fleetdm/fleet/v4@${{ github.ref_name }}