docs: use sentence case for headings

CONTRIBUTING.md

@@ -14,7 +14,7 @@ We're writing the webmail we wanted in 2026 and didn't find: a JMAP-native clien
 
 If that sounds like your kind of project, we'd love the help.
 
-## Join the Community
+## Join the community
 
 You don't need to be an expert to contribute. A dev environment that won't start, a bug you're not sure how to report, a translation you're stuck on: Discord is the fastest way to get unstuck and to meet the people working on this.
 
@@ -26,9 +26,9 @@ You don't need to be an expert to contribute. A dev environment that won't start
 
 ---
 
-## Getting Started
+## Getting started
 
-### Development Setup
+### Development setup
 
 1. **Fork and clone** the repository:
 
@@ -61,7 +61,7 @@ You don't need to be an expert to contribute. A dev environment that won't start
 
    Then open http://localhost:3000.
 
-### Code Quality
+### Code quality
 
 Before submitting a pull request, ensure your code passes all checks:
 
@@ -91,7 +91,7 @@ Run a single unit test file with `npx vitest run lib/__tests__/<name>.test.ts`,
 
 The integration suite needs Docker and takes several minutes; it has its own setup notes and findings log in [integration/README.md](integration/README.md). New behavior that touches mail/folder synchronization or multi-account handling belongs there.
 
-## Code Style Guidelines
+## Code style guidelines
 
 ### TypeScript
 
@@ -100,7 +100,7 @@ The integration suite needs Docker and takes several minutes; it has its own set
 - Avoid `any` types when possible
 - Use meaningful variable and function names
 
-### React Components
+### React components
 
 - Use functional components with hooks
 - Keep components focused and single-purpose
@@ -160,9 +160,9 @@ For a right-to-left language, also add the code to `rtlLocales` in `i18n/directi
 
 Run `npm run test:translations` afterwards - it checks the locale files for structural drift against English.
 
-## Pull Request Process
+## Pull request process
 
-### Before Submitting
+### Before submitting
 
 1. **Create a feature branch**:
 
@@ -191,7 +191,7 @@ Run `npm run test:translations` afterwards - it checks the locale files for stru
    - Screenshots for UI changes
    - Reference to any related issues
 
-### Commit Message Convention
+### Commit message convention
 
 Follow the conventional commits format:
 
@@ -211,7 +211,7 @@ fix: resolve attachment download issue
 docs: update README with keyboard shortcuts
 ```
 
-## Project Structure
+## Project structure
 
 ```
 webmail/

FEATURES.md

@@ -54,7 +54,7 @@
 - Trusted senders live in their own JMAP address book
 - Autocomplete on To, Cc, and Bcc
 
-## Filters & Templates
+## Filters & templates
 
 - Server-side filters as JMAP Sieve Scripts (RFC 9661)
 - A visual rule builder: conditions on From, To, Subject, Size, Body, Attachment and more, each matching multiple values, with actions to move, forward, star, or discard
@@ -73,7 +73,7 @@
 - Cut, copy, paste, duplicate; favorites; recent files
 - JMAP sharing (RFC 9670) for files and folders. Pick a user or group from the principal picker and grant read, read/write, or manager. Shared items get an indicator, and anything other principals share with you appears under "Shared with me".
 
-## Security & Privacy
+## Security & privacy
 
 - External content stays blocked until you say otherwise, and trusted senders are remembered
 - HTML sanitized through DOMPurify
@@ -111,7 +111,7 @@
 - The browser's `Accept-Language` picks the first language, and the choice persists per user
 - `NEXT_PUBLIC_DEFAULT_LOCALE` sets the fallback, `NEXT_PUBLIC_LOCALE_PREFIX` the URL prefix
 
-## Identity & Multi-Account
+## Identity & multi-account
 
 - Run several accounts at once and switch instantly, each keeping its own session. The 5-account cap lifts on HTTP/2 servers; on HTTP/1.1, browser connection pooling still sets the limit.
 - An account switcher showing connection status, and a default account
@@ -123,7 +123,7 @@
 - Several JMAP servers per deployment, optionally auto-picked by email domain
 - Custom JMAP endpoints on the login form, when `ALLOW_CUSTOM_JMAP_ENDPOINT` permits it
 
-## Admin & Extensibility
+## Admin & extensibility
 
 - A setup wizard runs on first launch and walks through JMAP servers, OAuth/OIDC, the session secret, logging, branding (uploads included), and the admin password. It writes to the admin config dir, so `.env.local` stays untouched.
 - The Stalwart admin dashboard, its policy sections collapsed into one tabbed page

README.md

@@ -70,7 +70,7 @@ The wizard writes to `ADMIN_CONFIG_DIR` (`./data/admin` by default). Setting `JM
 </tr>
 </table>
 
-## Overview
+## What Bulwark includes
 
 Bulwark is a full webmail suite. It bundles the four apps most self-hosters end up wanting:
 
@@ -85,7 +85,7 @@ Full feature list: **[FEATURES.md](FEATURES.md)**.
 
 ---
 
-## Quick Start
+## Quick start
 
 ### Docker
 
@@ -101,7 +101,7 @@ docker compose up -d
 
 On first launch, open `http://localhost:3000` and the setup wizard takes over. Installs that already define `JMAP_SERVER_URL` skip it and keep the env-managed flow under [Configuration](#configuration).
 
-### From Source
+### From source
 
 ```bash
 git clone https://github.com/bulwarkmail/webmail.git
@@ -308,7 +308,7 @@ Then point your reverse proxy at the container without stripping the prefix. The
 
 </details>
 
-## Keyboard Shortcuts
+## Keyboard shortcuts
 
 | Key                  | Action                  |
 | -------------------- | ----------------------- |
@@ -331,7 +331,7 @@ Then point your reverse proxy at the container without stripping the prefix. The
 
 In the composer: `Ctrl/Cmd`+`Enter` sends, `Ctrl/Cmd`+`Shift`+`Enter` opens scheduled send, and `t` opens the template picker.
 
-## Tech Stack
+## Tech stack
 
 |               |                                                   |
 | ------------- | ------------------------------------------------- |