Support c-style comments in JSON

Debate rages about whether JSON should have comments. The specification
says it shouldn't but the author of JSON suggested that if you want to
use JSON for configuration, then pipe it through jsmin before parsing.

So that's what we do, using a tiny JSON minifier from
https://github.com/getify/JSON.minify/tree/python

Closes #135

docs/configuration.md

@@ -110,14 +110,15 @@ But for now, consider the following example snippet:
 {
   "configurations": {
     "example-debug-configuration": {
+      // This is a single-line comment  explaining the purpose
       "adapter": "example-adapter-name",
       "variables": {
-        "SecretToken": {
+        "SecretToken": { // Variables should start with upper-case letters
           "shell" : [ "cat", "${HOME}/.secret_token" ]
         }
       },
       "configuration": {
-        "request": "launch",
+        "request": "launch" /* or it could be "attach" */,
         "program": [
           "${fileBasenameNoExtension}",
           "-c", "configuration_file.cfg",
@@ -364,6 +365,25 @@ The following variables are provided:
 * `${fileExtname}` - the current opened file's extension
 * `${cwd}` - the current working directory of the active window on launch
 
+## Appendix: Configuration file format
+
+The configuration files are text files which must be UTF-8 encoded. They
+contain a single JSON object, along with optional comments.
+
+Comments are "c-style", i.e.:
+
+* `// single line comment ...`
+* `/* inline comment */`
+
+There is much debate about whether JSON files should contain comments. I have
+added them because they are useful in the context of configuration files.
+Unforutnately this may mean your editor doesn't like them (they are strictly
+invalid JSON) so it's up to you if you use them.
+
+Technically, Vimspector uses [JSON
+minify](https://github.com/getify/JSON.minify) to strip comments before parsing
+the JSON.
+
 ## Appendix: Editor configuration
 
 If you would like some assistance with writing the JSON files, and your editor