replace shasum so random pw gets created

Dockerfile

@@ -21,12 +21,14 @@ RUN \
         libboost-system-dev \
         libboost-test-dev \
         libboost-thread-dev \
+        libdigest-sha-perl \
         libevent-dev \
         libminiupnpc-dev \
         libssl-dev \
         libtool \
         libzmq3-dev \
         libzmq5 \
+        perl \
         pkg-config \
     && \
     apt-get clean && \

README.markdown

@@ -17,7 +17,26 @@ This outputs the config file, including the
 rpc user password (either from `BITCOIND_RPCPASSWORD` or randomly
 generated) to the logs on startup.
 
+# Security
+
+This container logs the rpc password into the container's logfiles.
+
 # Versions
 
 * sneak/bitcoind:latest -> bitcoind master
 * sneak/bitcoind:v0.18.1 -> bitcoind v0.18.1
+
+# Usage
+
+```
+docker run \
+        --name bitcoind \
+        -v /storage/bitcoin/bitcoind:/var/lib/bitcoind \
+        --env BITCOIND_RPCUSER=username \
+        --env BITCOIND_RPCPASSWORD=supersecret \
+        -p 8333:8333 \
+        -p 8332:8332 \
+        -d sneak/bitcoind:v0.18.1
+
+docker logs -f bitcoind
+```