docs: document celestia-node metrics

# Summary
This document highlights the most important metrics, what they are, and what an acceptable value is for them.

## Problem
Node metrics aren’t defined anywhere.

What do the metrics on this dashboard mean, and what ranges should node operators aim to meet for them?
[Grafana](https://celestia-metrics.chaintrails.io/d/fdz036p9r5pmoe/foundation-bridge-node-overview?orgId=1&refresh=15m)

## What are the most important metrics and what do they mean? What are acceptable values?

| Metric | Description | Acceptable value | Subcategory |
|--------|-------------|------------------|-------------|
| hdr_store_head_height_gauge (local store height) | to check height: for local store | chain head | ? |
| hdr_sync_subjective_head_gaug | to check height: for local store | | |
| what the node thinks is latest height (can be misleading if rpc you're connected to is behind for example) | chain head | ? | |
| Build Version | version of celestia-node | [https://docs.celestia.org/nodes/participate](https://docs.celestia.org/nodes/participate) | Overview |
| Uptime | uptime - measured in days | As long as possible? lol | Overview |
| Current Height | current height of bridge node | Tip of chain | Overview |
| Blocks To Sync | Number of blocks required to sync before syncing to tip of chain | 0 | Overview |
| Full Peer Count | Full DA node peer count | >0 | Overview |
| Archival Peer Count | Archival full DA node peer count | >0 | Overview |
| PFB count | ??? | | Overview |
| Store Put Latency Distribution | ??? | | Overview |
| Store Put Latency | ??? | | Overview |
| Store Put Operations | ??? | | Overview |
| Store Get Car AVG Latency | ??? | | Overview |
| Car BlockStore Get AVG Latency | ??? | | Overview |
| Store Get Car Operations / Minute | ??? | | Overview |
| Dagstore Shards | ??? | | Overview |
| shrex nd server total responses | ??? | | Overview |
| shrex eds server total responses / Minute | ??? | | Overview |
| [BlockStore] Cache Hit Ratio | ??? | | Overview |
| [BlockStore] Cache Miss Ratio | ??? | | Overview |
| [Recent] Cache Hit Ratio | ??? | | Overview |
| [Recent] Cache Miss Ratio | ??? | | Overview |
| hdr/p2p/msg/sub Operation Time | ??? | | Headers |
| hdr/p2p/sub/msg Avg Size | ??? | | Headers |
| hdr/p2p/sub Number Of Msgs / Minute | ??? | | Headers |
| hdr/p2p/exch/headers Served | ??? | | Headers |
| hdr/p2p/exch/head Operations/Sec | ??? | | Headers |
| hdr/p2p/exch/head Operation Time | ??? | | Headers |
| hdr/p2p/exch/head Avg Latency | ??? | | Headers |
| Store/Get/blockstore Operation Time | ??? | | Store |
| Store/Get/blockstore Operations/Sec | ??? | | Store |
| Store/Get/blockstore Avg Latency | ??? | | Store |
| Store/Get/car Operation Time | ??? | | Store |
| Store/Get/car Operations/Sec | ??? | | Store |
| Store/Get/car Avg Latency | ??? | | Store |
| Store/Get/dah Operation Time | ??? | | Store |
| Store/Get/car Operations/Sec | ??? | | Store |
| Store/Get/dah Avg Latency | ??? | | Store |
| Store/has Operation Time | ??? | | Store |
| Store/has Operations/Sec | ??? | | Store |
| Store/has Avg Latency | ??? | | Store |
| Store/put Operation Time | ??? | | Store |
| Peers [Full] | Amount of peers | ? | Peers |
| Peers [Archival] | Amount of archival peers | ? | Peers |

# Solution
- [ ] Add these metrics to this page: [https://docs.celestia.org/nodes/celestia-node-metrics](https://docs.celestia.org/nodes/celestia-node-metrics)