[wiki/MUTN] Add shell completions troubleshooting guide

wiki/MUTN/completions.md

@@ -0,0 +1,32 @@
+### ZSH completions not working?
+Make sure your ~/.zshrc contains the following:
+```shell
+autoload -Uz compinit && compinit
+```
+...and then restart your shell.
+***
+### Bash completions not working? 
+Install your distribution's 'bash-completion' package or source the completion script manually.
+
+For most environments, this would mean adding the following to your ~/.bashrc:
+```shell
+source /usr/share/bash-completion/completions/mutn
+```
+Note that this directory is different on FreeBSD.
+
+FreeBSD:
+```shell
+source /usr/local/share/bash-completion/completions/mutn
+```
+...and then restart your shell.
+
+*Please note that Bash completions are slightly more limited than ZSH completions, and as such, new entries will not be auto-completed until the completions script is re-sourced.*
+***
+### PowerShell completions not working?
+Ensure you are using modern PowerShell (7+) as opposed to the built-in Windows PowerShell.
+
+Currently, completions must be manually installed and sourced in your PowerShell profile as such:
+```shell
+Set-PSReadlineKeyHandler -Key Tab -Function Complete  # this line is optional; it makes tab completion function more similarly to Bash/ZSH
+. <drive letter>:\path\to\mutn.ps1
+```

wiki/main.md

@@ -9,7 +9,7 @@ Crossed out items have not yet been added to the wiki.
 
 [~~Windows Quirks~~](https://github.com/rwinkhart/MUTN/blob/main/wiki/MUTN/quirks.md)
 
-[~~Shell Completions Troubleshooting~~](https://github.com/rwinkhart/MUTN/blob/main/wiki/MUTN/completions.md)
+[Shell Completions Troubleshooting](https://github.com/rwinkhart/MUTN/blob/main/wiki/MUTN/completions.md)
 
 [~~Known Bugs~~](https://github.com/rwinkhart/MUTN/blob/main/wiki/MUTN/bugs.md)
 ### libmutton Information (will likely be moved to libmutton repository in the future)