Google Drive recently added an option to search menu of Google Docs. The new search option is available when you click Help. There is a keyboard shortcut as well. Alt + / brings up the search field in the menu.
Here is the official post from Google Drive.
Moving fast and being efficient is an important part of getting work done. Whether you’re trying to change a font size, insert a comment, get to spell check, or align a paragraph — it’s nice to have technology that can keep up with your train of thought!
That’s why the search box in Docs lets you take quick actions in just a few keystrokes. Visit the ‘Help’ menu or use Alt / to get to the search box, then search for what you’d like to do — all without having to click through the menu bar.
Now an animated gif showing off this feature in action.
Hope you find this useful!