Move duplicate include_path docs to prose

There's no need to repeat ourselves, and having it makes the
documentation fiddlier to read.

Author: jakelishman

docs/parse.rst

@@ -9,15 +9,17 @@ This package currently contains two public functions, both of which create a
 while :func:`loads` takes the program itself as a string.  Their internals are very similar, so both
 offer the same API.
 
-Both functions can optionally take an `include_path` argument, which contains the directories that
-should be searched (in order) to find files specified by ``include`` statements in OpenQASM 2.  The
-include ``qelib1.inc`` is treated as a system include; this will always be found, regardless of the
-import settings. This helps ensure correct mapping to gates that Qiskit has builtin definitions for.
-
 .. autofunction:: load
 
 .. autofunction:: loads
 
+Both of these loading functions also take an argument `include_path`, which is an iterable of
+directory names to use when searching for files in ``include`` statements.  The directories are
+tried from index 0 onwards, and the first match is used.  The import ``qelib1.inc`` is treated
+specially; it is always found before looking in the include path, and contains exactly the content
+of the `paper describing the OpenQASM 2 language <https://arxiv.org/abs/1707.03429>`__.  The gates
+in this include file are mapped to standard gates provided by Qiskit.
+
 In cases where the lexer or parser fails due to an invalid OpenQASM 2 file, the conversion functions
 will raise an error with a message explaining what the failure is, and where in the file it
 occurred.

src-python/qiskit_qasm2/__init__.py

@@ -26,16 +26,6 @@ def loads(string: str, include_path: Iterable[Union[str, os.PathLike]] = (".",))
 
     :param string: The OpenQASM 2 program in a string.
     :type string: str
-    :param include_path: An iterable of directories to use when searching for include files.  These
-        are tried in order, from index 0 onwards, and the first match is used.  The import
-        `qelib1.inc` is treated as a system include, and will always be found regardless of the
-        value of this argument.
-
-        By default, this contains only the current working directory.
-    :type include_path: Iterable[Union[str, os.PathLike]]
-
-    :raises QASM2ParseError: If the OpenQASM 2 program is invalid, or otherwise cannot be converted
-        to Qiskit format.
 
     :return: A circuit object representing the same OpenQASM 2 program.
     :rtype: ~qiskit.circuit.QuantumCircuit
@@ -56,22 +46,11 @@ def load(
     :param filename: A filename for a file that contains an OpenQASM 2 program.
     :type filename: str
 
-    :param include_path: An iterable of directories to use when searching for include files.  These
-        are tried in order, from index 0 onwards, and the first match is used.  The import
-        `qelib1.inc` is treated as a system include, and will always be found regardless of the
-        value of this argument.
-
-        By default, this contains only the current working directory.
-    :type include_path: Iterable[Union[str, os.PathLike]]
-
     :param include_file_directory: Whether to add the directory of the input file to the
         `include_path`, and if so, whether to `append` it to search last, or `prepend` it to search
         first.  Pass `None` to suppress adding this directory entirely.
     :type include_file_directory: ``None``, ``"append"`` or ``"prepend"``.
 
-    :raises QASM2ParseError: If the OpenQASM 2 program is invalid, or otherwise cannot be converted
-        to Qiskit format.
-
     :return: A circuit object representing the same OpenQASM 2 program.
     :rtype: ~qiskit.circuit.QuantumCircuit
     """