Add std4 library to bookshelf.

lake-manifest.json

@@ -19,6 +19,12 @@
     "rev": "071464ac36e339afb7a87640aa1f8121f707a59a",
     "name": "aesop",
     "inputRev?": "master"}},
+  {"git":
+   {"url": "https://github.com/leanprover/std4.git",
+    "subDir?": null,
+    "rev": "6006307d2ceb8743fea7e00ba0036af8654d0347",
+    "name": "std4",
+    "inputRev?": "6006307d2ceb8743fea7e00ba0036af8654d0347"}},
   {"git":
    {"url": "https://github.com/leanprover/std4",
     "subDir?": null,

lakefile.lean

@@ -6,6 +6,9 @@ package «bookshelf»
 require mathlib from git
   "https://github.com/leanprover-community/mathlib4.git" @
     "0107c50abf149a48b5b9ad08a0b2a2093bcb567a"
+require std4 from git
+  "https://github.com/leanprover/std4.git" @
+    "6006307d2ceb8743fea7e00ba0036af8654d0347"
 
 @[default_target]
 lean_lib «Bookshelf» {