fix(docs): missing line breaks in why-base page

Path: /base-chain/quickstart/why-base

**Page:** https://docs.base.org/base-chain/quickstart/why-base
**File:** `docs/base-chain/quickstart/why-base.mdx`

## Description

Two bullet list items are missing a trailing newline, causing them to run directly into the next paragraph with no space or line break.

**Occurrence 1** — "A platform for building innovative apps" section:
> - Accept payments from anyone, easily**It's fast, cheap, and permissionless...**

**Occurrence 2** — "Expansive developer tools" section:
> - Robust developer tooling**But there’s more: Base apps can be launched...**

## Suggested fix

Add a blank line after each affected bullet to separate the list from the following paragraph. For example:

```mdx
- Accept payments from anyone, easily

It's fast, cheap, and permissionless...
```