Add Expensify Mono font and update code styling

- Introduced 'Expensify Mono' font with regular and bold weights in _fonts.scss.
- Updated _main.scss to apply 'Expensify Mono' font to code elements with custom styling.
- Added new font files: ExpensifyMono-Regular.woff, ExpensifyMono-Regular.woff2, ExpensifyMono-Bold.woff, and ExpensifyMono-Bold.woff2.

docs/_sass/_fonts.scss

@@ -26,6 +26,20 @@
   src: url('/assets/fonts/ExpensifyNewKansas-MediumItalic.woff2') format('woff2'), url('/assets/fonts/ExpensifyNewKansas-MediumItalic.woff') format('woff');
 }
 
+@font-face {
+  font-family: Expensify Mono;
+  font-weight: 400;
+  font-style: normal;
+  src: url('/assets/fonts/ExpensifyMono-Regular.woff2') format('woff2'), url('/assets/fonts/ExpensifyMono-Regular.woff') format('woff');
+}
+
+@font-face {
+  font-family: Expensify Mono;
+  font-weight: 700;
+  font-style: normal;
+  src: url('/assets/fonts/ExpensifyMono-Bold.woff2') format('woff2'), url('/assets/fonts/ExpensifyMono-Bold.woff') format('woff');
+}
+
 * {
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;

docs/_sass/_main.scss

@@ -144,6 +144,21 @@ p {
     padding-bottom: 20px;
 }
 
+code {
+    font-family: 'Expensify Mono', 'Helvetica Neue', 'Helvetica', Arial, sans-serif;
+    border-width: 1px;
+    border-style: solid;
+    border-radius: 5px;
+    border-color: var(--color-borders);
+    background-color: var(--color-highlightBG);
+    line-height: 20px;
+    padding-left: 5px;
+    padding-right: 5px;
+    font-size: 13px;
+    margin-top: 0px;
+    margin-bottom: 0px;
+}
+
 body,
 button,
 input,