core: Tidy contributor onboarding, fix typos. (#12700)

core: Tidy contributor onboarding.

- Fixes typos.
- Fixes stale links.
- Tidies Makefile so that Poetry env is optional for hygiene commands.
- Remove mismatched YAML naming.
- Uses shebang on Python scripts.
- Document semver usage.
- Redirect OpenAPI schema.

Signed-off-by: Teffen Ellis <592134+GirlBossRush@users.noreply.github.com>

.vscode/settings.json

@@ -1,26 +1,4 @@
 {
-    "cSpell.words": [
-        "akadmin",
-        "asgi",
-        "authentik",
-        "authn",
-        "entra",
-        "goauthentik",
-        "jwe",
-        "jwks",
-        "kubernetes",
-        "oidc",
-        "openid",
-        "passwordless",
-        "plex",
-        "saml",
-        "scim",
-        "slo",
-        "sso",
-        "totp",
-        "traefik",
-        "webauthn"
-    ],
     "todo-tree.tree.showCountsInTree": true,
     "todo-tree.tree.showBadges": true,
     "yaml.customTags": [