go-md2man: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/go-md2man - from package: golang-github-cpuguy83-go-md2man

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/go-md2man - from package: go-md2man

You may install the required package with command apt-get install {package}

Error in other languages:
go-md2man: bevel nie gevind nie
go-md2man: comandă negăsită
go-md2man: comando não encontrado
go-md2man: commande introuvable
go-md2man: command not found
go-md2man: käsku ei ole
go-md2man: không tìm thấy lệnh
go-md2man: komanda nerasta
go-md2man: Kommando nicht gefunden.
go-md2man: kommandot finns inte
go-md2man: komut yok
go-md2man: nie znaleziono polecenia
go-md2man: níor aimsíodh an t-ordú
go-md2man: no se encontró la orden
go-md2man: no s'ha trobat l'ordre
go-md2man: opdracht niet gevonden
go-md2man: parancs nem található
go-md2man: perintah tidak ditemukan
go-md2man: príkaz nenájdený
go-md2man: příkaz nenalezen
go-md2man: команда не найдена
go-md2man: командата не е открита
go-md2man: 命令找不到
go-md2man: コマンドが見つかりません