Improve the glossary

[salmad3]

Context

• Many terms that aren't yet in the glossary should be.
• There is an opportunity writing style edits, including condensing the long explanations for certain content.

Done Criteria

• Add the following terms:

- Routing
- Stream
- Hash
- Key
- Packet
- Frame
- DNS
- Encryption
- Authentication
- Gossip
- Latency
- Firewall
- Routing table
- TCP
- UDP
- WebSockets
- SDP
- STUN
- TURN
- Certificate Authority (CA)
- RLPx
- DTLS
- Signaling server
- Multicodecs
- (feel free to add others)

• Condense definitions for terms and phrases that are too long
• Create a hierarchical organization for related terms / phrases. For instance:
• Addresses
  • IP Address
  • Multiaddresses
• Hash
  • Multihash
• NAT traversal
  • STUN
  • TURN
• Node
  • Boot node

Why Important

The glossary is key tool for understanding the concepts in the libp2p documentation, and serves as a general reference point for fundamental terms and phrases, which should exhaustive and up-to-date.

[ElPaisano]

@DannyS03 I can take this issue