Merge #16643: doc: Add ZMQ dependencies to the Fedora build instructions

dc1bc1c doc: Add ZMQ dependencies to Fedora build (Hennadii Stepanov)

Pull request description:

  Without `zeromq-devel` package on Fedora 30:
  ```
  $ ./configure | grep zmq
  configure: WARNING: libzmq version 4.x or greater not found, disabling
    with zmq      = no
  ```

  With installed `zeromq-devel`:
  ```
  $ ./configure | grep zmq
    with zmq      = yes
  ```

  Also this PR improves style in the `miniupnpc` related paragraphs.

ACKs for top commit:
  emilengler:
    Concept ACK dc1bc1c
  practicalswift:
    ACK dc1bc1c -- diff looks correct
  fanquake:
    ACK dc1bc1c - tested in a Fedora 30 Docker container. Other changes match the Ubuntu & Debian docs above.

Tree-SHA512: 89b083a6256e8d0bcb9f0b193af84bc680843fdbb4a3e8871086477875250ad0ae214ce08797fc70c0cb04a2969632840c805a2a10a433763ee31cd1aa793bac

Author: fanquake

doc/build-unix.md

@@ -96,7 +96,7 @@ Otherwise, you can build from self-compiled `depends` (see above).
 To build Bitcoin Core without wallet, see [*Disable-wallet mode*](/doc/build-unix.md#disable-wallet-mode)
 
 
-Optional (see --with-miniupnpc and --enable-upnp-default):
+Optional (see `--with-miniupnpc` and `--enable-upnp-default`):
 
     sudo apt-get install libminiupnpc-dev
 
@@ -130,10 +130,14 @@ Build requirements:
 
     sudo dnf install gcc-c++ libtool make autoconf automake openssl-devel libevent-devel boost-devel libdb4-devel libdb4-cxx-devel python3
 
-Optional:
+Optional (see `--with-miniupnpc` and `--enable-upnp-default`):
 
     sudo dnf install miniupnpc-devel
 
+ZMQ dependencies (provides ZMQ API):
+
+    sudo dnf install zeromq-devel
+
 To build with Qt 5 you need the following:
 
     sudo dnf install qt5-qttools-devel qt5-qtbase-devel protobuf-devel