docs: fix British English spellings to American English

Author: ryoppippi

docs/guide/getting-started.md

@@ -71,9 +71,9 @@ Now that you have your first report, explore these features:
 
 1. **[Weekly Reports](/guide/weekly-reports)** - Track usage patterns by week
 2. **[Monthly Reports](/guide/monthly-reports)** - See usage aggregated by month
-3. **[Session Reports](/guide/session-reports)** - Analyse individual conversations
+3. **[Session Reports](/guide/session-reports)** - Analyze individual conversations
 4. **[Statusline](/guide/statusline)** - Real-time usage display for Claude Code status bar
-5. **[Configuration](/guide/configuration)** - Customise ccusage behaviour
+5. **[Configuration](/guide/configuration)** - Customize ccusage behavior
 
 ## Common Use Cases
 

docs/guide/index.md

@@ -56,7 +56,7 @@ Unlike other CLI tools, we pay extreme attention to bundle size. ccusage achieve
 - Compact real-time usage display for Claude Code status bar hooks
 - Session cost, daily cost, and block cost tracking
 - Burn rate calculations with visual indicators
-- Context usage percentage with colour-coded alerts
+- Context usage percentage with color-coded alerts
 
 ### 🔧 Flexible Configuration