Doc fixes for process functions (Bug#30349)

* doc/lispref/processes.texi (Asynchronous Processes): Explain what
the 'stopped' state means for a pipe process.
* src/process.c (Fmake_process, Fmake_pipe_process)
(Fmake_serial_process, Fmake_network_process):
* lisp/subr.el (start-process):
* lisp/net/tls.el (open-tls-stream):
* lisp/net/starttls.el (starttls-open-stream):
* lisp/net/gnutls.el (open-gnutls-stream): Remove meaningless phrase
"specify an output stream" phrase from docstring.

doc/lispref/processes.texi

@@ -728,8 +728,11 @@ Initialize the process query flag to @var{query-flag}.
 @xref{Query Before Exit}.
 
 @item :stop @var{stopped}
-If @var{stopped} is non-@code{nil}, start the process in the
-stopped state.
+If @var{stopped} is non-@code{nil}, start the process in the stopped
+state.  In the stopped state, a pipe process does not accept incoming
+data, but you can send outgoing data.  The stopped state is set by
+@code{stop-process} and cleared by @code{continue-process}
+(@pxref{Signals to Processes}).
 
 @item :filter @var{filter}
 Initialize the process filter to @var{filter}.  If not specified, a

lisp/net/gnutls.el

@@ -124,7 +124,7 @@ Args are NAME BUFFER HOST SERVICE.
 NAME is name for process.  It is modified if necessary to make it unique.
 BUFFER is the buffer (or `buffer-name') to associate with the process.
  Process output goes at end of that buffer, unless you specify
- an output stream or filter function to handle the output.
+ a filter function to handle the output.
  BUFFER may be also nil, meaning that this process is not associated
  with any buffer
 Third arg is name of the host to connect to, or its IP address.

lisp/net/starttls.el

@@ -270,7 +270,7 @@ Args are NAME BUFFER HOST PORT.
 NAME is name for process.  It is modified if necessary to make it unique.
 BUFFER is the buffer (or `buffer-name') to associate with the process.
  Process output goes at end of that buffer, unless you specify
- an output stream or filter function to handle the output.
+ a filter function to handle the output.
  BUFFER may be also nil, meaning that this process is not associated
  with any buffer
 Third arg is name of the host to connect to, or its IP address.

lisp/net/tls.el

@@ -204,7 +204,7 @@ Args are NAME BUFFER HOST PORT.
 NAME is name for process.  It is modified if necessary to make it unique.
 BUFFER is the buffer (or buffer name) to associate with the process.
  Process output goes at end of that buffer, unless you specify
- an output stream or filter function to handle the output.
+ a filter function to handle the output.
  BUFFER may be also nil, meaning that this process is not associated
  with any buffer
 Third arg is name of the host to connect to, or its IP address.

lisp/subr.el

@@ -2110,10 +2110,10 @@ and the file name is displayed in the echo area."
 NAME is name for process.  It is modified if necessary to make it unique.
 BUFFER is the buffer (or buffer name) to associate with the process.
 
-Process output (both standard output and standard error streams) goes
-at end of BUFFER, unless you specify an output stream or filter
-function to handle the output.  BUFFER may also be nil, meaning that
-this process is not associated with any buffer.
+Process output (both standard output and standard error streams)
+goes at end of BUFFER, unless you specify a filter function to
+handle the output.  BUFFER may also be nil, meaning that this
+process is not associated with any buffer.
 
 PROGRAM is the program file name.  It is searched for in `exec-path'
 \(which see).  If nil, just associate a pty with the buffer.  Remaining

src/process.c

@@ -1618,9 +1618,8 @@ to make it unique.
 
 :buffer BUFFER -- BUFFER is the buffer (or buffer-name) to associate
 with the process.  Process output goes at end of that buffer, unless
-you specify an output stream or filter function to handle the output.
-BUFFER may be also nil, meaning that this process is not associated
-with any buffer.
+you specify a filter function to handle the output.  BUFFER may be
+also nil, meaning that this process is not associated with any buffer.
 
 :command COMMAND -- COMMAND is a list starting with the program file
 name, followed by strings to give to the program as arguments.
@@ -2310,8 +2309,8 @@ arguments are defined:
 
 :buffer BUFFER -- BUFFER is the buffer (or buffer-name) to associate
 with the process.  Process output goes at the end of that buffer,
-unless you specify an output stream or filter function to handle the
-output.  If BUFFER is not given, the value of NAME is used.
+unless you specify a filter function to handle the output.  If BUFFER
+is not given, the value of NAME is used.
 
 :coding CODING -- If CODING is a symbol, it specifies the coding
 system used for both reading and writing for this process.  If CODING
@@ -3025,8 +3024,8 @@ the value of PORT is used.
 
 :buffer BUFFER -- BUFFER is the buffer (or buffer-name) to associate
 with the process.  Process output goes at the end of that buffer,
-unless you specify an output stream or filter function to handle the
-output.  If BUFFER is not given, the value of NAME is used.
+unless you specify a filter function to handle the output.  If BUFFER
+is not given, the value of NAME is used.
 
 :coding CODING -- If CODING is a symbol, it specifies the coding
 system used for both reading and writing for this process.  If CODING
@@ -3688,9 +3687,8 @@ to make it unique.
 
 :buffer BUFFER -- BUFFER is the buffer (or buffer-name) to associate
 with the process.  Process output goes at end of that buffer, unless
-you specify an output stream or filter function to handle the output.
-BUFFER may be also nil, meaning that this process is not associated
-with any buffer.
+you specify a filter function to handle the output.  BUFFER may be
+also nil, meaning that this process is not associated with any buffer.
 
 :host HOST -- HOST is name of the host to connect to, or its IP
 address.  The symbol `local' specifies the local host.  If specified