CURLOPT_ACCEPT_ENCODING.3: remove "four" as they are five

... instead just list the supported encodings.

Reported-by: ProceduralMan on github
Fixes curl#9614
Closes curl#9615

docs/libcurl/opts/CURLOPT_ACCEPT_ENCODING.3

@@ -46,11 +46,11 @@ set ("") to ask for an Accept-Encoding: header to be used that contains all
 built-in supported encodings.
 
 Alternatively, you can specify exactly the encoding or list of encodings you
-want in the response. Four encodings are supported: \fIidentity\fP, meaning
-non-compressed, \fIdeflate\fP which requests the server to compress its
-response using the zlib algorithm, \fIgzip\fP which requests the gzip
+want in the response. The following encodings are supported: \fIidentity\fP,
+meaning non-compressed, \fIdeflate\fP which requests the server to compress
+its response using the zlib algorithm, \fIgzip\fP which requests the gzip
 algorithm, (since curl 7.57.0) \fIbr\fP which is brotli and (since curl
-7.72.0) \fIzstd\fP which is zstd.  Provide them in the string as a
+7.72.0) \fIzstd\fP which is zstd. Provide them in the string as a
 comma-separated list of accepted encodings, like: \fB"br, gzip, deflate"\fP.
 
 Set \fICURLOPT_ACCEPT_ENCODING(3)\fP to NULL to explicitly disable it, which