clarify local dev dex-explorer workflow

[TalDerei]

manually migrating the UI package to the dex-explorer has a few downsides: (1) it requires a repack every time a change is made in the host UI package to propagate changes, (2) any update in the web UI package would require a corresponding update to the dex-explorer UI package, and vice versa, to maintain parity. This isn’t an ideal dev workflow.

Instead, we should create a symlink or emulate the prax dev workflows (prax-wallet/prax#149) to establish a more canonical way to automatically watch changes.