message: Add API docs for LMDBDataset
  Add API docs for LMDBDataset
  Additional corrections to API docs
  Fix missing curly brace
diff: op {
  graph_op_name: "LMDBDataset"
  visibility: HIDDEN
  + in_arg {
  + name: "filenames"
  + description: <<END
  +A scalar or a vector containing the name(s) of the binary file(s) to be
  +read.
  +END
  + }
  + summary: "Creates a dataset that emits the key-value pairs in one or more LMDB files."
  + description: <<END
  +The Lightning Memory-Mapped Database Manager, or LMDB, is an embedded binary
  +key-value database. This dataset can read the contents of LMDB database files,
  +the names of which generally have the `.mdb` suffix.
  +
  +Each output element consists of a key-value pair represented as a pair of
  +scalar string `Tensor`s, where the first `Tensor` contains the key and the
  +second `Tensor` contains the value.
  +
  +LMDB uses different file formats on big- and little-endian machines.
  +`LMDBDataset` can only read files in the format of the host machine.
  +END
  }
  