docs: misc improvements (#3773)

* correct misc typos

We also seem to be favoring `behavior` over `behaviour`.

* bump MkDocs version

* resolve errors shown when buildg docs

* improve the Rspamd page

* behaviour -> behavior

Streamline the usage of this word. The majority used behavior, so I
opted to go with this way of spelling it.

* Apply suggestions from code review

---------

Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>

docs/content/config/advanced/auth-ldap.md

@@ -56,7 +56,7 @@ These variables specify the LDAP filters that dovecot uses to determine if a use
 This is split into the following two lookups, both using `%u` as the placeholder for the full login name ([see dovecot documentation for a full list of placeholders](https://doc.dovecot.org/configuration_manual/config_file/config_variables/)). Usually you only need to set `DOVECOT_USER_FILTER`, in which case it will be used for both filters.
 
 - `DOVECOT_USER_FILTER` is used to get the account details (uid, gid, home directory, quota, ...) of a user.
-- `DOVECOT_PASS_FILTER` is used to get the password information of the user, and is in pretty much all cases identical to `DOVECOT_USER_FILTER` (which is the default behaviour if left away).
+- `DOVECOT_PASS_FILTER` is used to get the password information of the user, and is in pretty much all cases identical to `DOVECOT_USER_FILTER` (which is the default behavior if left away).
 
 If your directory doesn't have the [postfix-book schema](https://github.com/variablenix/ldap-mail-schema/blob/master/postfix-book.schema) installed, then you must change the internal attribute handling for dovecot. For this you have to change the `pass_attr` and the `user_attr` mapping, as shown in the example below:
 

docs/content/config/advanced/ipv6.md

@@ -60,7 +60,7 @@ Enable `ip6tables` support so that Docker will manage IPv6 networking rules as w
     ```
 
     - `experimental: true` is currently required for `ip6tables: true` to work.
-    - `userland-proxy` setting [can potentially affect connection behaviour][gh-pull-3244-proxy] for local connections.
+    - `userland-proxy` setting [can potentially affect connection behavior][gh-pull-3244-proxy] for local connections.
 
     Now restart the daemon if it's running: `systemctl restart docker`.
 
@@ -99,7 +99,7 @@ Next, configure a network with an IPv6 subnet for your container with any of the
 
             ??? tip "Override the implicit `default` network"
 
-                You can optionally avoid the service assignment by [overriding the `default` user-defined network that Docker Compose generates](docker-docs-network-compose-default). Just replace `dms-ipv6` with `default`.
+                You can optionally avoid the service assignment by [overriding the `default` user-defined network that Docker Compose generates][docker-docs-network-compose-default]. Just replace `dms-ipv6` with `default`.
 
                 The Docker Compose `default` bridge is not affected by settings for the default `bridge` (aka `docker0`) in `/etc/docker/daemon.json`.
 
@@ -180,7 +180,7 @@ curl --max-time 5 http://[2001:db8::1]:80
 !!! info "IPv6 ULA address priority"
 
     DNS lookups that have records for both IPv4 and IPv6 addresses (_eg: `localhost`_) may prefer IPv4 over IPv6 (ULA) for private addresses, whereas for public addresses IPv6 has priority. This shouldn't be anything to worry about, but can come across as a surprise when testing your IPv6 setup on the same host instead of from a remote client.
-    
+
     The preference can be controlled with [`/etc/gai.conf`][networking-gai], and appears was configured this way based on [the assumption that IPv6 ULA would never be used with NAT][networking-gai-blog]. It should only affect the destination resolved for outgoing connections, which for IPv6 ULA should only really affect connections between your containers / host. In future [IPv6 ULA may also be prioritized][networking-gai-rfc].
 
 [docker-subnets]: https://straz.to/2021-09-08-docker-address-pools/#what-are-the-default-address-pools-when-no-configuration-is-given-vanilla-pools

docs/content/config/advanced/optional-config.md

@@ -35,7 +35,7 @@ This is a list of all configuration files and directories which are optional or
 - **whitelist_clients.local:** Whitelisted domains, not considered by postgrey. Enter one host or domain per line.
 - **spamassassin-rules.cf:** Anti-spam rules for Spamassassin. (Docs: [FAQ - SpamAssassin Rules][docs-faq-spamrules])
 - **fail2ban-fail2ban.cf:** Additional config options for `fail2ban.cf`. (Docs: [Fail2Ban][docs-fail2ban])
-- **fail2ban-jail.cf:** Additional config options for fail2ban's jail behaviour. (Docs: [Fail2Ban][docs-fail2ban])
+- **fail2ban-jail.cf:** Additional config options for fail2ban's jail behavior. (Docs: [Fail2Ban][docs-fail2ban])
 - **amavis.cf:** replaces the `/etc/amavis/conf.d/50-user` file
 - **dovecot.cf:** replaces `/etc/dovecot/local.conf`. (Docs: [Override Dovecot Defaults][docs-override-dovecot])
 - **dovecot-quotas.cf:** list of custom quotas per mailbox. (Docs: [Accounts][docs-accounts-quota])

docs/content/config/advanced/podman.md

@@ -107,7 +107,7 @@ The `PERMIT_DOCKER` variable in the `mailserver.env` file allows to specify trus
 #### Use the slip4netns network driver
 
 The second workaround is slightly more complicated because the `compose.yaml` has to be modified.
-As shown in the [fail2ban section](../../security/fail2ban/#podman-with-slirp4netns-port-driver) the `slirp4netns` network driver has to be enabled.
+As shown in the [fail2ban section](../security/fail2ban.md#podman-with-slirp4netns-port-driver) the `slirp4netns` network driver has to be enabled.
 This network driver enables podman to correctly resolve IP addresses but it is not compatible with
 user defined networks which might be a problem depending on your setup.