Refactor CONTRIBUTING.md and add conventions stub

CONTRIBUTING.md

@@ -5,6 +5,10 @@ description: Get involved in GTFOBins.
 permalink: /contributing/
 ---
 
+## File format
+
+Feel free to use any file in the [`_gtfobins/`] folder as an example.
+
 Each entry is defined in a [YAML][] file placed in the [`_gtfobins/`][] folder and named like the executable (binary or script) it refers, without any extension. The file contains a single document enclosed in delimiters: `---` and `...`. The general structure is the following:
 
 ```yaml
@@ -44,14 +48,18 @@ Some functions support additional fields:
 
 - `reverse-shell` and `bind-shell` allows a `limited` flag that is `true` when the example is not able to spawn a full TTY shell.
 
-- `file-write`, `file-read`, `upload`, and `download` allows a `limited` flag that is `true` when the example is not able handle arbitrary binary data.
+- `file-write`, `file-read`, `upload`, and `download` allows a `limited` flag that is `true` when the example is not able handle arbitrary binary data;
+
+- `inherit` requires a `from` field that is the name of another executable that the example enables.
 
 Some contexts support additional fields:
 
 - `suid` allows a `limited` flag that is `true` when the example only works with distributions whose default shell does not drop SUID privileges;
 
 - `capabilities` requires a `list` of Linux [capabilities](https://man7.org/linux/man-pages/man7/capabilities.7.html) in the format `CAP_*` that are needed in order to execute this function with bypassed permissions.
 
+### Aliases
+
 Additionally, it is possible to add _aliases_ with:
 
 ```yaml
@@ -62,9 +70,55 @@ alias: <gtfobin>
 
 In this case, this entry is an alias of an existing `<gtfobin>`.
 
-Feel free to use any file in the [`_gtfobins/`] folder as an example.
+## Conventions
+
+### Placeholders
+
+Use the following placeholder values where appropriate:
+
+| Type                 | Value                  |
+|----------------------|------------------------|
+| Shell executable     | `/bin/sh`              |
+| Command executable   | `/bin/id`              |
+| Network port         | `12345`                |
+| Data to be written   | `DATA`                 |
+| Whatever value       | `x...x`                |
+| Input file           | `/path/to/input-file`  |
+| Output file          | `/path/to/output-file` |
+| Attacker host domain | `attacker.com`         |
+
+### Multiline strings
+
+If a multiline string is needed, use the `-` YAML literal variant, i.e., `|-`, for example:
+
+```
+some-field: |-
+  Lorem ipsum...
+```
+
+### Links
+
+If needed, link to other entries using relative URLs, e.g, `[gtfobin](../gtfobin)`.
+
+## Local development
+
+To test local changes, start a local instance with:
+
+```
+make serve
+```
+
+This will spin a Docker container that builds the website, and serves it from <http://0.0.0.0:4000>. Changes to local files are automatically applied.
+
+Before submitting any pull request, make sure the linter completes successfully:
+
+```
+make lint
+```
+
+Then use `make clean` to clean everything up.
 
 [YAML]: https://yaml.org/
-[`_gtfobins/`]: https://github.com/GTFOBins/GTFOBins.github.io/tree/master/_gtfobins
 [`_data/functions.yml`]: https://github.com/GTFOBins/GTFOBins.github.io/blob/master/_data/functions.yml
 [`_data/contexts.yml`]: https://github.com/GTFOBins/GTFOBins.github.io/blob/master/_data/contexts.yml
+[`_gtfobins/`]: https://github.com/GTFOBins/GTFOBins.github.io/tree/master/_gtfobins

assets/style.scss

@@ -113,6 +113,16 @@ fieldset {
     }
 }
 
+table {
+    &, th, td {
+        border: 1px solid $foreground;
+    }
+
+    th, td {
+        padding: 0.25em 0.5em;
+    }
+}
+
 // permalink on headings
 
 h2, h3, h4, h5, h5 {
@@ -210,6 +220,10 @@ h2, h3, h4, h5, h5 {
         width: 100%;
         border-spacing: 0;
 
+        &, th, td {
+            border: none;
+        }
+
         thead {
             th {
                 padding: 1em;