Fix docs

.github/workflows/doc.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v2

doc/api.rst

@@ -62,7 +62,7 @@ participate in an overload resolution if the latter is not a string.
 .. doxygenfunction:: vprint(string_view fmt, format_args args)
 
 .. doxygenfunction:: print(std::FILE *f, format_string<T...> fmt, T&&... args)
-.. doxygenfunction:: vprint(std::FILE* f, string_view fmt, format_args args)
+.. doxygenfunction:: vprint(std::FILE *f, string_view fmt, format_args args)
 
 Compile-time Format String Checks
 ---------------------------------