[website] Improve typography by adopting Inter font (#2232)

Author: wuchong

website/src/css/custom.css

@@ -34,7 +34,7 @@
   --ifm-color-primary-lighter: #0682ff;
   --ifm-color-primary-lightest: #2893ff;
   --ifm-code-font-size: 90%;
-  --ifm-font-family-base: "Roboto",Segoe UI,Roboto,Ubuntu,Cantarell,Helvetica,sans-serif,Apple Color Emoji,Segoe UI Emoji,Android Emoji,EmojiSymbols,EmojiOne Mozilla,Twemoji Mozilla,Segoe UI Symbol,Noto Color Emoji;
+  --ifm-font-family-base: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
   --docusaurus-highlighted-code-line-bg: #E2E9F3;
 
   --ifm-menu-color-background-active: #edeefa99;