docs: add share version 1 to specs (#3955)

Closes #3867

specs/src/consensus.md

@@ -32,6 +32,7 @@
 | `SHARE_INFO_BYTES`                      | `uint64` | `1`          | `byte`  | The number of bytes used for [share](data_structures.md#share) information                                                                                               |
 | `SHARE_RESERVED_BYTES`                  | `uint64` | `4`          | `byte`  | The number of bytes used to store the index of the first transaction in a transaction share. Must be able to represent any integer up to and including `SHARE_SIZE - 1`. |
 | `SHARE_SIZE`                            | `uint64` | `512`        | `byte`  | Size of transaction and blob [shares](data_structures.md#share), in bytes.                                                                                               |
+| `SignerSize`                            | `int`    | `20`         | `byte`  | The number of bytes used to store the signer in a [share](data_structures.md#share).                                                                                     |
 | `STATE_SUBTREE_RESERVED_BYTES`          | `uint64` | `1`          | `byte`  | Number of bytes reserved to identify state subtrees.                                                                                                                     |
 | `UNBONDING_DURATION`                    | `uint32` |              | `block` | Duration, in blocks, for unbonding a validator or delegation.                                                                                                            |
 | `v1.Version`                            | `uint64` | `1`          |         | First version of the application. Breaking changes (hard forks) must update this parameter.                                                                              |

specs/src/figures/first_share_with_signer.dot

@@ -0,0 +1,25 @@
+digraph G {
+    node [shape = record, penwidth = 0];
+
+    share [label=<
+    <table border="0" cellborder="1" cellspacing="0">
+        <tr>
+            <td align="left" border="0" cellpadding="0">0</td>
+            <td align="left" border="0" cellpadding="0">1</td>
+            <td align="left" border="0" cellpadding="0">29</td>
+            <td align="left" border="0" cellpadding="0">30</td>
+            <td align="left" border="0" cellpadding="0">34</td>
+            <td align="left" border="0" cellpadding="0">54</td>
+            <td align="left" border="0" cellpadding="0">512</td>
+        </tr>
+        <tr>
+            <td width="8" cellpadding="4">namespace version</td>
+            <td width="8" cellpadding="4">namespace id</td>
+            <td width="1" cellpadding="4">info byte</td>
+            <td width="4" cellpadding="4">sequence length</td>
+            <td width="4" cellpadding="4">signer</td>
+            <td width="200" cellpadding="4">blob1</td>
+        </tr>
+    </table>
+    >];
+}

specs/src/shares.md

@@ -23,6 +23,12 @@ User submitted transactions are split into shares (see [share splitting](#share-
 
 ## Share Format
 
+### Share Version
+
+The share version is a 7-bit big-endian unsigned integer that is used to indicate the version of the [share format](#share-format). A new share version MUST be introduced if the share format changes in a way that is not backwards compatible. There are two share versions [share version 0](#share-version-0) and [share version 1](#share-version-1).
+
+### Share Version 0
+
 Every share has a fixed size [`SHARE_SIZE`](./consensus.md#constants). The share format below is consistent for all shares:
 
 - The first [`NAMESPACE_VERSION_SIZE`](./consensus.md#constants) bytes of a share's raw data is the namespace version of that share (denoted by "namespace version" in the figure below).
@@ -44,9 +50,17 @@ Continuation share in a sequence:
 
 Since raw data that exceeds [`SHARE_SIZE`](./consensus.md#constants)`-`[`NAMESPACE_SIZE`](./consensus.md#constants)`-`[`SHARE_INFO_BYTES`](./consensus.md#constants) `-` [`SEQUENCE_BYTES`](./consensus.md#constants) bytes will span more than one share, developers MAY choose to encode additional metadata in their raw blob data prior to inclusion in a Celestia block. For example, Celestia transaction shares encode additional metadata in the form of "reserved bytes".
 
-### Share Version
+### Share Version 1
+
+Share version 1 is similar to share version 0 with the addition of a `signer` field. The signer is located after the sequence length in the first share. The signer is [`SIGNER_SIZE`](./consensus.md#constants) bytes.
+
+First share in a sequence with signer:
+
+![figure 3: first share with signer](./figures/first_share_with_signer.svg)
+
+Continuation share in a sequence:
 
-The share version is a 7-bit big-endian unsigned integer that is used to indicate the version of the [share format](#share-format). The only supported share version is `0`. A new share version MUST be introduced if the share format changes in a way that is not backwards compatible.
+![figure 4: share continuation](./figures/share_continuation.svg)
 
 ## Transaction Shares