Add documentation

[kimicol]

Fill README.md with informations about tokens and scores.

Documentation about csv format used to classify scores shall also be added.

[CLAassistant]

All committers have signed the CLA.

[ofaurax]

Have look to my proposal edits, then resubmit review, thanks!

[ofaurax]

Suggested change

	Tokens are used to regulate access to scores. Nobody can access to scores without it, and it has an expiration date.
	Tokens are used to regulate access to scores. Nobody can access scores without one, and they have an expiration date.

[ofaurax]

Suggested change

	If the used link to the scores is used for malicious purpose, it can be quickly deactivated to stop access from the leaked link. Then a new one can be created to provide a new access to target users.
	If the used link to the scores is used for malicious purpose, it can be quickly deactivated to stop access from the leaked link, by simply removing the token. Then, a new one can be created to provide a new access to target users.

[ofaurax]

Suggested change

To create a new token, create a file in repository `private/tokens/` in the format `YYYYMMDD-KEY.txt`, by replacing `YYYYMMDD` by a given date (in format year-month-day) which is the limit of activation of the token (passed this date, the token is disabled) and `KEY` by any alphanumeric string of characters (preferably randomly generated).

To create a new token, create a file in repository `private/tokens/` in the format `YYYYMMDD-KEY.txt`, by replacing `YYYYMMDD` by a given date (in format year-month-day) which is the date after which the token is disabled, and `KEY` by any alphanumeric string of characters. `KEY` *must be* randomly generated, because anyone that knows can access all scores. All this process can be handled by `/admin/token.php`. This script *MUST* be protected from public access.

[ofaurax]

Suggested change

	The content of this file is ignored.
	The content of token files is ignored.

[ofaurax]

Suggested change

	To access to the website with the token, the URL shall be: *www.mywebsite.com/?token=KEY* with *KEY* the actual `KEY` used at the end of the created file name.
	To access to the website with the token, the URL shall be: *www.example.com/?token=KEY* with *KEY* the actual `KEY` used at the end of the created file name.

[ofaurax]

Suggested change

	To add a new set of music scores here, create a new directory with the code of the score in csv (ex: "F058" for "1ere Symphonie en Ut Majeur" described in `Archives_HMAP_140126.csv`.
	To add a new set of music scores here, create a new directory with the score reference in csv (ex: "F058" for "1ere Symphonie en Ut Majeur" described in `Archives_HMAP_140126.csv`.

[ofaurax]

Suggested change

	Then in that directory, add all scores.
	Then in that directory (e.g. `private/docs/F058`), add all scores.