docs/libcurl: polish the single-line descriptions

- use imperative form
- use lowercase
- no period
- unify some phrases
- fix curl_multi_socket and curl_multi_socket_all to keep their own
  descriptions

Closes #14062

docs/libcurl/curl_multi_socket.md

@@ -16,7 +16,7 @@ Protocol:
 
 # NAME
 
-curl_multi_socket - reads/writes available data
+curl_multi_socket - read/write available data
 
 # SYNOPSIS
 
@@ -24,47 +24,37 @@ curl_multi_socket - reads/writes available data
 #include <curl/curl.h>
 CURLMcode curl_multi_socket(CURLM *multi_handle, curl_socket_t sockfd,
                             int *running_handles);
-
-CURLMcode curl_multi_socket_all(CURLM *multi_handle,
-                                int *running_handles);
 ~~~
 
 # DESCRIPTION
 
-These functions are deprecated. Do not use. See
-curl_multi_socket_action(3) instead.
+This function is deprecated. Do not use. See curl_multi_socket_action(3)
+instead.
 
 At return, the integer **running_handles** points to contains the number of
 still running easy handles within the multi handle. When this number reaches
 zero, all transfers are complete/done. Note that when you call
-curl_multi_socket_action(3) on a specific socket and the counter
-decreases by one, it DOES NOT necessarily mean that this exact socket/transfer
-is the one that completed. Use curl_multi_info_read(3) to figure out
-which easy handle that completed.
+curl_multi_socket(3) on a specific socket and the counter decreases by one, it
+DOES NOT necessarily mean that this exact socket/transfer is the one that
+completed. Use curl_multi_info_read(3) to figure out which easy handle that
+completed.
 
-The curl_multi_socket_action(3) functions inform the application about
-updates in the socket (file descriptor) status by doing none, one, or multiple
-calls to the socket callback function set with the
-CURLMOPT_SOCKETFUNCTION(3) option to curl_multi_setopt(3). They
-update the status with changes since the previous time the callback was
-called.
+The curl_multi_socket(3) functions inform the application about updates in the
+socket (file descriptor) status by doing none, one, or multiple calls to the
+socket callback function set with the CURLMOPT_SOCKETFUNCTION(3) option to
+curl_multi_setopt(3). They update the status with changes since the previous
+time the callback was called.
 
-Get the timeout time by setting the CURLMOPT_TIMERFUNCTION(3) option
-with curl_multi_setopt(3). Your application then gets called with
-information on how long to wait for socket actions at most before doing the
-timeout action: call the curl_multi_socket_action(3) function with the
-**sockfd** argument set to CURL_SOCKET_TIMEOUT. You can also use the
-curl_multi_timeout(3) function to poll the value at any given time, but
-for an event-based system using the callback is far better than relying on
-polling the timeout value.
+Get the timeout time by setting the CURLMOPT_TIMERFUNCTION(3) option with
+curl_multi_setopt(3). Your application then gets called with information on
+how long to wait for socket actions at most before doing the timeout action:
+call the curl_multi_socket_action(3) function with the **sockfd** argument set
+to CURL_SOCKET_TIMEOUT. You can also use the curl_multi_timeout(3) function to
+poll the value at any given time, but for an event-based system using the
+callback is far better than relying on polling the timeout value.
 
 Usage of curl_multi_socket(3) is deprecated, whereas the function is
-equivalent to curl_multi_socket_action(3) with **ev_bitmask** set to
-0.
-
-Force libcurl to (re-)check all its internal sockets and transfers instead of
-just a single one by calling curl_multi_socket_all(3). Note that there
-should not be any reason to use this function.
+equivalent to curl_multi_socket_action(3) with **ev_bitmask** set to 0.
 
 # EXAMPLE
 
@@ -86,8 +76,7 @@ int main(void)
 This function was added in libcurl 7.15.4, and is deemed stable since
 7.16.0.
 
-curl_multi_socket(3) is deprecated, use
-curl_multi_socket_action(3) instead!
+curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3) instead!
 
 # RETURN VALUE