docs: Make the short port names in the port/version sidebar lowercase.

To make it neater and simpler.

docs/conf.py

@@ -26,10 +26,10 @@ from collections import OrderedDict
 micropy_port = os.getenv('MICROPY_PORT') or 'pyboard'
 tags.add('port_' + micropy_port)
 ports = OrderedDict((
-    ('unix', ('unix', 'unix')),
-    ('pyboard', ('pyboard', 'the pyboard')),
-    ('wipy', ('WiPy', 'the WiPy')),
-    ('esp8266', ('ESP8266', 'the ESP8266')),
+    ('unix', 'unix'),
+    ('pyboard', 'the pyboard'),
+    ('wipy', 'the WiPy'),
+    ('esp8266', 'the ESP8266'),
 ))
 
 # The members of the html_context dict are available inside topindex.html
@@ -38,11 +38,10 @@ micropy_all_versions = (os.getenv('MICROPY_ALL_VERSIONS') or 'latest').split(','
 url_pattern = '%s/en/%%s/%%s' % (os.getenv('MICROPY_URL_PREFIX') or '/',)
 html_context = {
     'port':micropy_port,
-    'port_short_name':ports[micropy_port][0],
-    'port_name':ports[micropy_port][1],
+    'port_name':ports[micropy_port],
     'port_version':micropy_version,
     'all_ports':[
-        (port_name[0], url_pattern % (micropy_version, port_id))
+        (port_id, url_pattern % (micropy_version, port_id))
             for port_id, port_name in ports.items()
     ],
     'all_versions':[