Add brief description to some unix.* calls missing it

tool/net/help.txt

@@ -2828,7 +2828,7 @@ UNIX MODULE
 
     `env` is a string list table. Values are coerced to strings. No
     ordering requirement is imposed. By convention, each string has its
-    key and value divided by an equals sign without spaces. If this
+    key and value separated by an equals sign without spaces. If this
     parameter is not specified, it'll default to the C/C++ `environ`
     variable which is inherited from the shell that launched redbean.
     It's the responsibility of the user to supply a sanitized environ
@@ -3677,6 +3677,8 @@ UNIX MODULE
       ├─→ fd:int
       └─→ nil, unix.Errno
 
+    Creates socket endpoint for process communication.
+
     `family` defaults to `AF_INET` and can be:
 
     - `AF_INET`: Creates Internet Protocol Version 4 (IPv4) socket.
@@ -3975,6 +3977,8 @@ UNIX MODULE
       ├─→ data:str
       └─→ nil, unix.Errno
 
+    Receives message from a socket.
+
     `flags` may have any combination (using bitwise OR) of:
 
     - `MSG_WAITALL`
@@ -3987,6 +3991,8 @@ UNIX MODULE
       ├─→ data:str, unixpath:str
       └─→ nil, unix.Errno
 
+    Receives message from a socket.
+
     `flags` may have any combination (using bitwise OR) of:
 
     - `MSG_WAITALL`
@@ -4063,6 +4069,8 @@ UNIX MODULE
       ├─→ oldhandler:func|int, flags:int, mask:unix.Sigset
       └─→ nil, unix.Errno
 
+    Changes action taken upon receipt of a specific signal.
+
     `sig` can be one of:
 
     - `unix.SIGINT`