Add library crate definition back

src/glossary.rst

@@ -3744,6 +3744,14 @@ lexical element
 A :dt:`lexical element` is the most basic syntactic element in program
 text.
 
+.. _fls_r1sk7vdgckym:
+
+library crate
+^^^^^^^^^^^^^
+
+:dp:`fls_3m8lg4mdc2x0`
+A :dt:`library crate` is a :t:`crate` that is not a :t:`binary crate`.
+
 .. _fls_vdhaa61g6kah:
 
 lifetime

src/program-structure-and-compilation.rst

@@ -138,6 +138,9 @@ The :t:`function` in scope of a :t:`binary crate`'s :t:`crate root module` under
 the :t:`name` ``main`` with a :t:`main function signature` is the :t:`binary
 crate`'s :t:`program entry point`.
 
+:dp:`fls_d9nn4yuiw1ja`
+A :t:`library crate` is a :t:`crate` that is not a :t:`binary crate`.
+
 :dp:`fls_Mf62VqAhoZ3c`
 A :t:`proc-macro crate` is a :t:`crate` whose :t:`crate type` is ``proc-macro``.