Don't require IDL directories to start with 'v'

For doc generation, don't assume IDL dirs start with 'v'.

They may be "version" directories, or any other way users want to group
their protocol definitions.

interface_gen/docs.py

@@ -110,15 +110,15 @@ def __init__(self, input_path: Path, gen_path: Path):
 
     def _enumerate(self):
         self.versions: list[Version] = []
-        version_dirs = self.root_path.glob("v*")
+        version_dirs = self.root_path.glob("*")
         for vdir in version_dirs:
-            vname = vdir.name[1:]  # strip leading 'v'
             avdl_files = vdir.glob("*.avdl")
             protos = []
             for avdl in avdl_files:
                 protocol = Protocol.from_avdl(avdl, self.gen_path)
                 protos.append(protocol)
-            self.versions.append(Version(vname, vdir, protos))
+            v = Version(vdir.name, vdir, protos)
+            self.versions.append(v)
 
     def generate_index(self, output_dir: Path):
         index_path = output_dir / "index.md"