We should write the offical document for https://docs.python.org/3/library/

• Document string.templatelib in the Library reference section
• Find all mentions of f-strings in the current documentation and decide whether there should also be a reference to t-strings
• Add AST nodes to the ast docs
• Glossary
• Add new t-string roles to lexical-analysis.rst section with the _f-strings role and make sure it covers t-strings appropriately.
• Lexical analysis, adjust f-strings section (probably keep one section and talk about f-string and t-string syntax in it, since it's so closely tied)
• Add BUILD_INTERPOLATION and BUILD_TEMPLATE to the dis docs, probably somewhere near BUILD_TUPLE
• Lexical analysis, adjust String and Bytes literals section (Pending changes in this PR by @encukou .)
• Update the Template strings section of Doc/library/string.rst to clarify that this is unrelated to t-strings (it's $-strings)
• A section after the f-strings part of the tutorial where perhaps we show writing a function. I'm 50-50 on this (the cookbook might be enough.)

This can be a follow-on PR, but probably shouldn't be part of the first PR?:

• Consider building a "Python string formatting cookbook" that explains when you might use each of Python's increasingly many formatting features. (One question we got asked a lot at PyCon was: "are f-strings deprecated"?)