chroma: add page (#4603)

pages/common/chroma.md

@@ -0,0 +1,16 @@
+# chroma
+
+> Chroma is a general-purpose syntax highlighting library and corresponding command, for Go.
+> More information: <https://github.com/alecthomas/chroma>.
+
+- Highlight a source file with python lexer and output to terminal:
+
+`chroma --lexer="{{python}}" {{source_file}}`
+
+- Highlight a source file with Go lexer and output to a HTML file:
+
+`chroma --lexer="{{go}}" --formatter="{{html}}" {{source_file}} > {{html_file}}`
+
+- Highlight a source file with C++ lexer and output to an SVG image, using the Monokai style:
+
+`chroma --lexer="{{c++}}" --formatter="{{svg}}" --syle="{{monokai}}" {{source_file}} > {{svg_file}}`