Add 'swap' command to docs

docs/SUMMARY.md

@@ -16,6 +16,7 @@
 * [split](commands/split.md)
 * [palette](commands/palette.md)
 * [remap](commands/remap.md)
+* [swap](commands/swap.md)
 * [pipeline](commands/pipeline.md)
 
 ### Pipelines

docs/commands/palette.md

@@ -19,6 +19,11 @@ Options:
   -V, --version          Print version
 ```
 
+### Palette Swapping
+
+This command can also generate a template for use with the Swap command by specifying `--format columns`. The output will be a PNG
+formatted image with a width of `2`, where each row is a unique colour found in the input image.
+
 ## Example
 
 ![](/images/Palette.png)
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docs/commands/swap.md

+# Command: Palette Swap
+
+Use a given mapping of colours to alter the input image. The palette image must contain 2 columns, and any colour in the
+input image will be checked against the first column of the palette, and if found will be replaced with the corresponding colour in the second column.
+
+## Usage
+
+```text
+Usage: crunch swap --palette <PALETTE> <INPUT> <OUTPUT>
+
+Arguments:
+  <INPUT>   The path to the image file
+  <OUTPUT>  The path to write the recoloured image
+  <PALETTE> The path to the palette image
+
+Options:
+  -p, --palette <PALETTE>  The path to the palette file containing the output colours
+  -h, --help               Print help
+  -V, --version            Print version
+```
+
+## Example
+
+![](/images/Swap.png)
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