Wrap default values in back ticks for tabhighlight and tabreverse

[itsf4llofstars]

Default value false in option "tabhighlight" documentation, options.md Line: 385 was missing back ticks.

Wrap false in back ticks for document formatting.

* `tabhighlight`: inverts the tab characters' (filename, save indicator, etc)
  colors with respect to the tab bar.

-   default value: false
+   default value: `false`

* `tabreverse`: reverses the tab bar colors when active.

---

Default value true in option "tabrevers" documentation, options.md Line: 389 was missing back ticks.

Wrap true in back ticks for document formatting.

* `tabreverse`: reverses the tab bar colors when active.

-   default value: true
+   default value: `true`

* `tabsize`: the size in spaces that a tab character should be displayed with.

Please let me know if there was any problems with this pull request. Thanks for the opportunity to contribute, and for the micro text editor.

Cheers
itsf4llofstars

[dmaluka]

Duplicate of #3615