Document system requirements (#1934)

## Proposed Changes

Document some minimal and recommended system specs for running Lighthouse on mainnet with a modest number of validators.

book/src/SUMMARY.md

@@ -3,6 +3,7 @@
 * [Introduction](./intro.md)
 * [Become a Testnet Validator](./testnet-validator.md)
 * [Installation](./installation.md)
+    * [System Requirements](./system-requirements.md)
     * [Pre-Built Binaries](./installation-binaries.md)
     * [Docker](./docker.md)
     * [Build from Source](./installation-source.md)

book/src/installation.md

@@ -13,4 +13,13 @@ Additionally, there are two extra guides for specific uses:
 - [Rapsberry Pi 4 guide](./pi.md).
 - [Cross-compiling guide for developers](./cross-compiling.md).
 
+## Minimum System Requirements
+
+* Dual-core CPU, 2015 or newer
+* 8 GB RAM
+* 128 GB solid state storage
+* 10 Mb/s download, 5 Mb/s upload broadband connection
+
+For more information see [System Requirements](./system-requirements.md).
+
 [WSL]: https://docs.microsoft.com/en-us/windows/wsl/about

book/src/system-requirements.md

@@ -0,0 +1,23 @@
+# System Requirements
+
+Lighthouse is able to run on most low to mid-range consumer hardware, but will perform best when
+provided with ample system resources. The following system requirements are for running a beacon
+node and a validator client with a modest number of validator keys (less than 100).
+
+## Minimum
+
+* Dual-core CPU, 2015 or newer
+* 8 GB RAM
+* 128 GB solid state storage
+* 10 Mb/s download, 5 Mb/s upload broadband connection
+
+During smooth network conditions, Lighthouse's database will fit within 15 GB, but in case of a long
+period of non-finality, it is **strongly recommended** that at least 128 GB is available.
+
+## Recommended
+
+* Quad-core AMD Ryzen, Intel Broadwell, ARMv8 or newer
+* 16 GB RAM
+* 256 GB solid state storage
+* 100 Mb/s download, 20 Mb/s upload broadband connection
+