Update README.md

Describe some common user problems that most users will have when trying to compile monodevelop on their own.
Fix shared projects compat issue with VS

Don't create or save build configurations for shared projects.
Don't add the location prefix to the DependentUpon property of files.

Fixes bug #20257 - Some shared projects created by XS can't be opened in VS.
Fix crash when cleaning project

It happens when cleaning a project that it has an incorrect configuration
mapping.

Fixes bug #20145 - On building Xamarin.Forms Shared solution, it displays
"Clean failed. Object reference not set to an instance of an object" in XS
status bar

Fixes bug #20251 - Xamarin 3: Unable to clean with 2 solutions loaded
Updated reference to md-addins
[Icons] [MonoDevelop.Ide] Fixing bad icon references
[Icons] [MonoDevelop.Ide] Removing obsolete stock icon overrides (md-gutter-error and md-gutter-warning)
Merge pull request #570 from Meai1/patch-1

Update README.md
Updated reference to md-addins
Revert F# bump since it broke the build
Fixed 'Bug 19908 - [Forms] Autocomplete doesn't work for the Children property of Forms layouts'
[Ide] Support MSBuild custom tools
[AspNet] Massive overhaul, in progress

* Cleaned and reorganized the codebase
* Moved ASP.NET unit test into separate assembly
* Removed automatic translation of C# project/file templates to other languages
* Removed build-time updating of Web Forms CodeBehind
* Removed unmaintained remote deployment system
* Use NuGet references in project templates
* Updated ASP.NET MVC templates to ASP.NET MVC 5
* Merged ASP.NET and ASP.NET MVC addins
* Added support for ASP.NET MVC in Web App projects
* Updated default doctypes to HTML5

Incomplete:
* Stetic is no longer used for UI panels
* Added automatic updating of WebForms CodeBehind on save
[XmlEditor] Massive cleanup, in progress

* Remove a lot of dead code
* Rename public types/namespace to be more meaningful

Incomplete
* Port old tests to new parser
* Reorganize namespaces/directories