Document remote authentication for SQL stored procedures

[tbantle22]

Closes #46.

The four remote-touching procedures (DOLT_CLONE, DOLT_FETCH, DOLT_PULL, DOLT_PUSH) each named --user and DOLT_REMOTE_PASSWORD in their option lists but didn't explain the actual SQL-server flow: that the env var lives on the server process (not the SQL session), what user/password to use for each backend (DoltHub / DoltLab / Hosted / another sql-server's remotesapi), or that all --user calls in a server process share one password.

Adds a new `### Authenticating to remotes` subsection at the top of `dolt-sql-procedures.md` covering all of the above, with an end-to-end example and the verbatim "must set DOLT_REMOTE_PASSWORD" error string. Each procedure's --user Options entry now cross-links into the new section.

Source: env var is read at call time on the server process per grpc_dial_provider.go:158.

🤖 Generated with Claude Code

[zachmu]

LGTM

Content is good, but maybe this deserves its own doc?

[tbantle22]

Done — pulled the "Authenticating to remotes" content out into its own page (/sql-reference/version-control/remote-authentication, "Authenticating to Remotes"), added under Version Control Features in the nav right after "Using Remotes". The four --user option entries in the procedures reference now just link to it instead of carrying the full explanation inline.

Heads-up: the branch was 43 commits behind dev and predated the catch-all routing + frontmatter-title refactors, so I rebased it onto current dev and force-pushed. That means the new page needs no .astro wrapper (the [...slug] route generates it) and its H1 is injected from the frontmatter title — but it also dismisses your prior approval, so this'll need a fresh look. Verified the build (141 pages, single H1, all cross-links resolve).