readd Wireshark SSL master secrets docs

docs/src/content/howto-wireshark-tls.md

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+---
+title: "Wireshark and SSL/TLS"
+menu:
+    howto:
+        weight: 1
+---
+
+# Wireshark and SSL/TLS Master Secrets
+
+The SSL/SSL master keys can be logged by mitmproxy so that external programs can
+decrypt SSL/TLS connections both from and to the proxy. Recent versions of
+Wireshark can use these log files to decrypt packets. See the [Wireshark wiki](https://wiki.wireshark.org/SSL#Using_the_.28Pre.29-Master-Secret) for more information.
+
+Key logging is enabled by setting the environment variable `SSLKEYLOGFILE` so
+that it points to a writable text file:
+{{< highlight bash  >}}
+SSLKEYLOGFILE="$PWD/.mitmproxy/sslkeylogfile.txt" mitmproxy
+{{< / highlight >}}
+You can also `export` this environment variable to make it persistent for all applications started from your current shell session.
+
+You can specify the key file path in Wireshark via `Edit -> Preferences ->
+Protocols -> SSL -> (Pre)-Master-Secret log filename`. If your SSLKEYLOGFILE
+does not exist yet, just create an empty text file, so you can select it in
+Wireshark (or run mitmproxy to create and collect master secrets).
+
+Note that `SSLKEYLOGFILE` is respected by other programs as well, e.g., Firefox
+and Chrome. If this creates any issues, you can use `MITMPROXY_SSLKEYLOGFILE`
+instead without affecting other applications.