Use unique identifiers for envvars

Add unique identifier for documented environment variables and remove
them from the index.

Fixes: #26

Author: adamtheturtle

sphinx_click/ext.py

@@ -140,6 +140,7 @@ def _format_arguments(ctx):
 def _format_envvar(param):
     """Format the envvars of a `click.Option` or `click.Argument`."""
     yield '.. envvar:: {}'.format(param.envvar)
+    yield '   :noindex:'
     yield ''
     if isinstance(param, click.Argument):
         param_ref = param.human_readable_name
@@ -156,6 +157,12 @@ def _format_envvars(ctx):
     params = [x for x in ctx.command.params if getattr(x, 'envvar')]
 
     for param in params:
+        yield '.. _{command_name}-{param_name}-{envvar}:'.format(
+            command_name=ctx.command.name,
+            param_name=param.name,
+            envvar=param.envvar,
+        )
+        yield ''
         for line in _format_envvar(param):
             yield line
         yield ''

tests/test_formatter.py

@@ -71,11 +71,17 @@ def cli():
 
         .. rubric:: Environment variables
 
+        .. _cli-param-PARAM:
+
         .. envvar:: PARAM
+           :noindex:
 
             Provide a default for :option:`--param`
 
+        .. _cli-arg-ARG:
+
         .. envvar:: ARG
+           :noindex:
 
             Provide a default for :option:`ARG`
         """).lstrip(), '\n'.join(output))