Update readme.rst

[jonhp]

fix broken link to file system flash layout

[Rotzbua]

the link is correct, no change required

[jonhp]

If I go to: https://arduino-esp8266.readthedocs.io/en/latest/ota_updates/readme.html
and then click on the "flash layout" link in "Keep in mind that the File system and EEPROM for example needs space too (one time) see flash layout." which is https://arduino-esp8266.readthedocs.io/en/latest/filesystem.rst#flash-layout
then I get a page that says
\ SORRY / \ / \ This page does / ] not exist yet. [ ,'|
That is not the result that I expect.
If I manually change the ".rst" to ".html" then the page displays as I would expect.
Maybe my proposed fix was incorrect, but I have now fully demonstrated the problem which is repeatable.

[Rotzbua]

You observed correctly that rst != html, but you look at the rendered page. The source are .rst files which are rendered by a compiler and are served as static html to an server.

So the source files are correct with rst, so it seems there is something wrong with the compiler or settings. Well some month ago @igrr changed all files from .md to .rst and I guess he forgot to change the configuration of readthedocs.io .

[pfeerick]

The RST file you modified should have :ref:`Flash layout` instead of `flash layout <../filesystem.html#flash-layout>`_ and then it should be fine, as it should then find the matching label and serve it properly. (Link to an external RST label).

[jonhp]

I took a shot at fixing this again and an on-page link. Not sure if I am any closer and not sure how to test these fixes either (hints anyone?).

[pfeerick]

AFAIK, that looks right. If you really want to validate it without waiting to see if someone can check it, it may be possible to follow the instructions here to get a test environment running, but going by the explicit external links reference, it seems like it should work ('cheat sheet' that I refer to whenever I need to learn more about reStructuredText formatting and markup). For straight 'markdown' formatting, you can view it on github, but some of the reStructuredText stuff needs to be processed, so can't just be shown as is.

[devyte]

Alright, if this is broken, it won't be worse than it already is, so I'm merging. If it's still broken afterwards, please take another shot at fixing the links.

[lrmoreno007]

" :ref: " is other way to make cross reference not discussed in #4409 . This need a label in the referenced file ("/doc/filesystem.rst") http://www.sphinx-doc.org/es/stable/markup/inline.html .

EXAMPLE:
In the file filesystem.rst:

Filesystem
==========

.. _flash-layout:

Flash layout
------------

Even though file system is stored on the same flash ......................

In the file /doc/ota_updates/readme.rst:

.......... EEPROM for example needs space too (one time) see :ref:`flash-layout`.

...........

But this work fine in Sphinx (ReadTheDocs) but not in Github.

[lrmoreno007]

And with flash layout <../filesystem.html#flash-layout>_ , will work too in Sphinx but not in Github.