Added the ZLib development package as a Linux requirement to the Main Tools section (#1558)

Fixes #1527

On Debian, the zlib1g-dev package is required to build and should be given as a requirement.

Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>

docs/project/contribution_tools.md

@@ -24,6 +24,7 @@ contributions.
         -   [Manual installations (not recommended)](#manual-installations-not-recommended)
         -   [Troubleshooting build issues](#troubleshooting-build-issues)
         -   [Troubleshooting debug issues](#troubleshooting-debug-issues)
+    -   [zlib (Linux-only)](#zlib-linux-only)
     -   [pre-commit](#pre-commit)
 -   [Optional tools](#optional-tools)
     -   [Carbon-maintained](#carbon-maintained)
@@ -225,6 +226,15 @@ Dwarf Error: DW_FORM_strx1 found in non-DWO CU
 It means that the version of GDB used is too old, and does not support the DWARF
 v5 format.
 
+### zlib (Linux-only)
+
+On **Linux**, you need to have the zlib headers installed. For Debian- and
+Ubuntu-based distributions, you can install the development package:
+
+```bash
+sudo apt install zlib1g-dev
+```
+
 ### pre-commit
 
 We use [pre-commit](https://pre-commit.com) to run