Rename doc/manual{src -> source}

This is needed to avoid this
https://github.com/mesonbuild/meson/issues/13774 when we go back to
making our subproject directory `src`.

doc/manual/src/release-notes/rl-0.13.md

@@ -1,55 +0,0 @@
-# Release 0.13 (2009-11-05)
-
-This is primarily a bug fix release. It has some new features:
-
-  - Syntactic sugar for writing nested attribute sets. Instead of
-    
-        {
-          foo = {
-            bar = 123;
-            xyzzy = true;
-          };
-          a = { b = { c = "d"; }; };
-        }
-    
-    you can write
-    
-        {
-          foo.bar = 123;
-          foo.xyzzy = true;
-          a.b.c = "d";
-        }
-    
-    This is useful, for instance, in NixOS configuration files.
-
-  - Support for Nix channels generated by Hydra, the Nix-based
-    continuous build system. (Hydra generates NAR archives on the fly,
-    so the size and hash of these archives isn’t known in advance.)
-
-  - Support `i686-linux` builds directly on `x86_64-linux` Nix
-    installations. This is implemented using the `personality()`
-    syscall, which causes `uname` to return `i686` in child processes.
-
-  - Various improvements to the `chroot` support. Building in a `chroot`
-    works quite well now.
-
-  - Nix no longer blocks if it tries to build a path and another process
-    is already building the same path. Instead it tries to build another
-    buildable path first. This improves parallelism.
-
-  - Support for large (\> 4 GiB) files in NAR archives.
-
-  - Various (performance) improvements to the remote build mechanism.
-
-  - New primops: `builtins.addErrorContext` (to add a string to stack
-    traces — useful for debugging), `builtins.isBool`,
-    `builtins.isString`, `builtins.isInt`, `builtins.intersectAttrs`.
-
-  - OpenSolaris support (Sander van der Burg).
-
-  - Stack traces are no longer displayed unless the `--show-trace`
-    option is used.
-
-  - The scoping rules for `inherit
-                    (e) ...` in recursive attribute sets have changed. The expression
-    *e* can now refer to the attributes defined in the containing set.