Initial swag at mdbook content.

This has the nng_a* to nng_c* content converted.
Various editorial changes have been made as well.

1 files changed, 45 insertions, 0 deletions

diff --git a/docs/reference/src/api/nng_close.md b/docs/reference/src/api/nng_close.md
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+# nng_close(3)
+
+## NAME
+
+nng_close --- close socket
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_close(nng_socket s);
+```
+
+## DESCRIPTION
+
+The `nng_close()` function closes the supplied socket, _s_.
+Messages that have been submitted for sending may be flushed or delivered,
+depending upon the transport.
+
+Further attempts to use the socket after this call returns will result
+in `NNG_ECLOSED`.
+Threads waiting for operations on the socket when this
+call is executed may also return with an `NNG_ECLOSED` result.
+
+> [!NOTE]
+> Closing the socket while data is in transmission will likely lead to loss
+> of that data.
+> There is no automatic linger or flush to ensure that the socket send buffers
+> have completely transmitted.
+> It is recommended to wait a brief period after calling
+> [`nng_send()`](nng_send.md) or similar functions, before calling this
+> function.
+
+## RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_ECLOSED`: The socket _s_ is already closed or was never opened.
+
+## SEE ALSO
+
+[nng_socket](nng_socket.md)