man: add available values for -c -M and -g options

doc/mscp.1.in

@@ -289,13 +289,21 @@ connection to the jump host described by
 .TP
 .B \-c \fICIPHER\fR
 Selects the cipher to use for encrypting the data transfer. See
+.B mscp -h
+or
+.B Ciphers
+in
 .UR https://\:www\:.libssh\:.org/\:features/
 libssh features
 .UE .
 
 .TP
 .B \-M \fIHMAC\fR
 Specifies MAC hash algorithms. See
+.B mscp -h
+or
+.B MAC hashes
+in
 .UR https://\:www\:.libssh\:.org/\:features/
 libssh features
 .UE .
@@ -311,6 +319,9 @@ libssh features
 .TP
 .B \-g \fICONGESTION\fR
 Specifies the TCP congestion control algorithm to use (Linux only).
+See
+.B sysctl net.ipv4.tcp_allowed_congestion_control
+for available values.
 
 .TP
 .B \-p

doc/mscp.rst

@@ -2,7 +2,7 @@
 MSCP
 ====
 
-:Date: v0.2.0-5-g08660bb
+:Date: v0.2.0-7-gab6649f
 
 NAME
 ====
@@ -166,18 +166,21 @@ OPTIONS
 
 **-c CIPHER**
    Selects the cipher to use for encrypting the data transfer. See
-   `libssh features <https://www.libssh.org/features/>`__.
+   **mscp -h** or **Ciphers** in `libssh
+   features <https://www.libssh.org/features/>`__.
 
 **-M HMAC**
-   Specifies MAC hash algorithms. See `libssh
-   features <https://www.libssh.org/features/>`__.
+   Specifies MAC hash algorithms. See **mscp -h** or **MAC hashes** in
+   `libssh features <https://www.libssh.org/features/>`__.
 
 **-C COMPRESS**
    Enables compression: yes, no, zlib, zlib@openssh.com. The default is
    none. See `libssh features <https://www.libssh.org/features/>`__.
 
 **-g CONGESTION**
    Specifies the TCP congestion control algorithm to use (Linux only).
+   See **sysctl net.ipv4.tcp_allowed_congestion_control** for available
+   values.
 
 **-p**
    Preserves modification times and access times (file mode bits are