Add useful bash commands sections

[opsmon]

Added new sections with practical bash commands:

• Process management (ps, top, kill, pkill, jobs, nohup)
• Networking (curl, wget, ping, netstat, ss, lsof)
• Text processing (cat, head, tail, sed, awk, diff)
• Archiving & compression (tar, zip, gzip)
• Permissions & ownership (chmod, chown)
• File search (find, grep with extended examples)
• System information (uname, free, df, du, lscpu)
• Date & time formatting
• Useful one-liners (find large files, http server, password generation, etc.)
• SSH & remote work (ssh, scp, rsync)
• Stream redirection (stdout, stderr, tee, heredoc)
• Xargs usage examples