Improve repo (#3148)

* remove 2 ebook of [Linkers and Loaders], [Learn Python The Hard Way]. ref issue:#3091, #3062

* Add CONTRIBUTING file of chinese version.

* Format text, update some description

* translate contribution md file.

* Add open Issue ref link

* Update some description in CONTRIBUTING And CONTRIBUTING-zh file.

* Update some description of zh version CONTRIBUTING.

* format md code to pass Travis CI check

* Fix The Travis CI check issue

* Fix The Travis CI check issue

* Fix The Travis CI check issue

* format md file to pass TCI check.

CONTRIBUTING.md

@@ -1,3 +1,5 @@
+*Read this in other languages: [中文](CONTRIBUTING-zh.md).*
+
 ## Contributor License Agreement
 By contributing you agree to the [LICENSE](https://github.com/EbookFoundation/free-programming-books/blob/master/LICENSE) of this repository.
 
@@ -6,8 +8,8 @@ By contributing you agree to respect the [Code of Conduct](https://github.com/Eb
 
 ## In a nutshell
 1. "A link to easily download a book" is not always a link to a *free* book. Please only contribute free content. Make sure it's free. We do not accept links to pages that *require* working email addresses to obtain books, but we welcome listings that request them.
-2. You don't have to know git: if you found something of interest which is *not already in this repo*, please open an issue with your links propositions.
-    - If you know git, please fork the repo and send pull requests.
+2. You don't have to know Git: if you found something of interest which is *not already in this repo*, please open an [Issue](https://github.com/EbookFoundation/free-programming-books/issues) with your links propositions.
+    - If you know Git, please Fork the repo and send pull requests.
 3. We have 5 kinds of lists. Choose the right one:
 
     - *Books* : PDF, HTML, ePub, a gitbook.io based site, a Git repo, etc.
@@ -16,7 +18,7 @@ By contributing you agree to respect the [Code of Conduct](https://github.com/Eb
     - *Podcasts and Screencasts* : Podcasts and screencasts.
     - *Problem Sets & Competitive Programming* : A website or software which lets you assess your programming skills by solving simple or complex problems, with or without code review, with or without comparing the results with other users.
 
-4. Make sure to follow the [guidelines below](#guidelines) and respect the [Markdown formatting](#formatting) of the files
+4. Make sure to follow the [guidelines below](#guidelines) and respect the [Markdown formatting](#formatting) of the files.
 
 5. Travis CI will run tests to make sure your lists are alphabetized and formatting rules are followed. Be sure to check that your changes pass the tests.
 
@@ -40,7 +42,7 @@ By contributing you agree to respect the [Code of Conduct](https://github.com/Eb
     + use the link with the most authoritative source (meaning author's website is better than editor's website is better than third party website)
     + if they link to different editions and you judge these editions are different enough to be worth keeping them, add a separate link with a note about each edition (see [Issue #2353](https://github.com/EbookFoundation/free-programming-books/issues/2353) to contribute to the discussion on formatting.)
 - prefer atomic commits (one commit by addition/deletion/modification) over bigger commits. No need to squash your commits before submitting a PR. (We will never enforce this rule as it's just a matter of convenience for the maintainers)
-- if the book is older, include the publication date with the title. 
+- if the book is older, include the publication date with the title.
 - include the author name or names where appropriate. You can shorten author lists with "et al."
 - if the book is not finished, and is still being worked on, add the "in process" notation, as described [below.](#in_process)
 - if an email address or account setup is requested before download is enabled, add language-appropriate notes in parentheses, e.g.: `(email address *requested*, not required)`
@@ -67,21 +69,21 @@ Example:
     * [Another Awesome Book](http://example.com/book.html)
     * [Some Other Book](http://example.com/other.html)
 
-- Don't put spaces between `]` and `(`
+- Don't put spaces between `]` and `(`:
 
 ```
 BAD : * [Another Awesome Book] (http://example.com/book.html)
 GOOD: * [Another Awesome Book](http://example.com/book.html)
 ```
 
-- If you include the author, use ` - ` (a dash surrounded by single spaces)
+- If you include the author, use ` - ` (a dash surrounded by single spaces):
 
 ```
 BAD : * [Another Awesome Book](http://example.com/book.html)- John Doe
 GOOD: * [Another Awesome Book](http://example.com/book.html) - John Doe
 ```
 
-- Put a single space between the link and its format
+- Put a single space between the link and its format:
 
 ```
 BAD : * [A Very Awesome Book](https://example.org/book.pdf)(PDF)
@@ -91,7 +93,7 @@ GOOD: * [A Very Awesome Book](https://example.org/book.pdf) (PDF)
 - Author comes before format:
 
 ```
-BAD : * [A Very Awesome Book](https://example.org/book.pdf)- Jane Roe
+BAD : * [A Very Awesome Book](https://example.org/book.pdf)- (PDF) Jane Roe
 GOOD: * [A Very Awesome Book](https://example.org/book.pdf) - Jane Roe (PDF)
 ```
 
@@ -106,12 +108,12 @@ GOOD: * [Another Awesome Book](http://example.com/) - John Doe (HTML) [(PDF, EPU
 - Include publication year in title for older books:
 
 ```
-BAD: * [A Very Awesome Book](https://example.org/book.html) - Jane Roe - 1970
+BAD : * [A Very Awesome Book](https://example.org/book.html) - Jane Roe - 1970
 GOOD: * [A Very Awesome Book (1970)](https://example.org/book.html) - Jane Roe
 ```
 
 <a name="in_process"></a>
-- In-process books 
+- In-process books:
 
 ```
 GOOD: * [Will Be Awesome Soon Book](http://example.com/book2.html) - John Doe (HTML) (:construction: *in process*)