[doc] Use consistent spelling/capitalization of names

Consistently use the following spelling for document formats,
programming languages, and names:

- Markdown
- Hjson
- JSON
- Verilog
- HTML
- GitHub
- CSS
- Python

Also avoid abbreviations:
- repo -> repository

Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/util/regtool.py b/util/regtool.py
index e96da59..9040cff 100755
--- a/util/regtool.py
+++ b/util/regtool.py
@@ -18,7 +18,7 @@
 from reggen import (gen_cheader, gen_ctheader, gen_dv, gen_html, gen_json,
                     gen_rtl, gen_selfdoc, validate, version)
 
-DESC = """regtool, generate register info from hjson source"""
+DESC = """regtool, generate register info from Hjson source"""
 
 USAGE = '''
   regtool [options]
@@ -42,7 +42,7 @@
                         metavar='file',
                         type=argparse.FileType('r'),
                         default=sys.stdin,
-                        help='input file in hjson type')
+                        help='input file in Hjson type')
     parser.add_argument('-d',
                         action='store_true',
                         help='Output register documentation (html)')