Fix broken markdown (#6273)

Author: ojh102

docs/How-to-Contribute.md

@@ -1,18 +1,18 @@
-RxJava is still a work in progress and has a long list of work documented in the [[Issues|https://github.com/ReactiveX/RxJava/issues]].
+RxJava is still a work in progress and has a long list of work documented in the [Issues](https://github.com/ReactiveX/RxJava/issues).
 
 
 If you wish to contribute we would ask that you:
-- read [[Rx Design Guidelines|http://blogs.msdn.com/b/rxteam/archive/2010/10/28/rx-design-guidelines.aspx]]
+- read [Rx Design Guidelines](http://blogs.msdn.com/b/rxteam/archive/2010/10/28/rx-design-guidelines.aspx)
 - review existing code and comply with existing patterns and idioms
 - include unit tests
 - stick to Rx contracts as defined by the Rx.Net implementation when porting operators (each issue attempts to reference the correct documentation from MSDN)
 
-Information about licensing can be found at: [[CONTRIBUTING|https://github.com/ReactiveX/RxJava/blob/1.x/CONTRIBUTING.md]].
+Information about licensing can be found at: [CONTRIBUTING](https://github.com/ReactiveX/RxJava/blob/2.x/CONTRIBUTING.md).
 
 ## How to import the project into Eclipse
 Two options below:
 
-###Import as Eclipse project 
+### Import as Eclipse project 
 
     ./gradlew eclipse
 
@@ -23,7 +23,7 @@ In Eclipse
 * Right click on the project in Package Explorer, select Properties - Java Compiler - Errors/Warnings - click Enable project specific settings.
 * Still in Errors/Warnings, go to Deprecated and restricted API and set Forbidden reference (access-rules) to Warning.
 
-###Import as Gradle project
+### Import as Gradle project
 
 You need the Gradle plugin for Eclipse installed.