correct suprious em dashes in documentation

-- is converted to an em dash by the MDX markdown parser.

This comes up in command line arguments, so just use inline code
blocks for them (as we already do in most places).

Also corrects two typos.

Fixes #3070.

docs/www/rpk-commands.md

@@ -137,7 +137,7 @@ Flags:
 
 OS support: ![Linux][linux]
 
-Initialize the configuration to bootstrap a cluster. --id is mandatory. `bootstrap` will expect the machine it's running on to have only one non-loopback IP address associated to it, and use it in the configuration as the node's address. If it has multiple IPs, --self must be specified. In that case, the given IP will be used without checking whether it's among the machine's addresses or not. The elements in --ips must be separated by a comma, no spaces. If omitted, the node will be configured as a root node, that otherones can join later.
+Initialize the configuration to bootstrap a cluster. `--id` is mandatory. `bootstrap` will expect the machine it's running on to have only one non-loopback IP address associated to it, and use it in the configuration as the node's address. If it has multiple IPs, `--self` must be specified. In that case, the given IP will be used without checking whether it's among the machine's addresses or not. The elements in `--ips` must be separated by a comma, no spaces. If omitted, the node will be configured as a root node, that other ones can join later.
 
 ```cmd
 Usage:
@@ -531,7 +531,7 @@ If `--seed-addr` is passed, it will be used to discover the rest of the cluster
 hosts via redpanda's Kafka API. If `--node-addrs` is passed, they will be used
 directly. Otherwise, `rpk generate prometheus-conf` will read the redpanda
 config file and use the node IP configured there. `--config` may be passed to
-especify an arbitrary config file.
+specify an arbitrary config file.
 
 ```cmd
 Usage: