fix validate docs build

Author: nebfield

docs/how-to/guides/validate.rst

@@ -12,18 +12,21 @@ Installation
 -------------
 
 Download the source code:
+
 ::
     $ git clone https://github.com/PGScatalog/pygscatalog.git
     $ cd pygscatalog/pygscatalog.validate
 
 Install the dependencies:
+
 ::
     $ poetry install
 
 Run with a virtual environment
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Start a new local virtual envrironment:
+
 ::
     $ poetry shell
     $ pgscatalog-validate --help
@@ -32,14 +35,17 @@ Or install the package in the current environment
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Build the wheel package:
+
 ::
     $ poetry build
 
 Install the built package in the current environment via pip:
+
 ::
     $ pip install dist/pgscatalog_validate-0.1-py3-none-any.whl
 
 Run
+
 ::
     pgscatalog-validate --help