Fix documentation/image links (#4025)

* Fix documentation/image links

* Fix sphinx warnings

Author: jhrcek

Diff for: docs/contributing/contributing.md

@@ -221,7 +221,7 @@ Run the benchmarks with `cabal bench`.
 
 It should take around 25 minutes and the results will be stored in the `bench-results` folder. To interpret the results, see the comments in the `bench/Main.hs` module.
 
-More details in [bench/README](../../bench/README.md)
+More details in [bench/README](https://github.com/haskell/haskell-language-server/blob/master/bench/README.md)
 
 ### Tracing
 
@@ -233,7 +233,7 @@ Adding support for new editors is fairly easy if the editor already has good sup
 In that case, there will likely be an editor-specific support system for this (like `lsp-mode` for Emacs).
 This will typically provide instructions for how to support new languages.
 
-In some cases you may need to write a small bit of additional client support, or expose a way for the user to set the server's [configuration options](#configuring-haskell-language-server) and
+In some cases you may need to write a small bit of additional client support, or expose a way for the user to set the server's [configuration options](../configuration.md#configuring-haskell-language-server) and
 for them to configure how the server is started.
 
 ## Building the docs

Diff for: docs/contributing/index.rst

@@ -6,4 +6,3 @@ Contributing
 
    contributing
    plugin-tutorial
-   releases

Diff for: docs/features.md

@@ -138,7 +138,7 @@ Provided by: `hls-call-hierarchy-plugin`
 
 Shows ingoing and outgoing calls for a function.
 
-![Call Hierarchy in VSCode](https://github.com/haskell/haskell-language-server/raw/2857eeece0398e1cd4b2ffb6069b05c4d2308b39/plugins/hls-call-hierarchy-plugin/call-hierarchy-in-vscode.gif)
+![Call Hierarchy in VSCode](../plugins/hls-call-hierarchy-plugin/call-hierarchy-in-vscode.gif)
 
 ## Highlight references
 
@@ -199,7 +199,7 @@ Rewrites imported names to be qualified.
 
 ![Qualify Imported Names Demo](../plugins/hls-qualify-imported-names-plugin/qualify-imported-names-demo.gif)
 
-For usage see the ![readme](../plugins/hls-qualify-imported-names-plugin/README.md).
+For usage see the [readme](https://github.com/haskell/haskell-language-server/blob/master/plugins/hls-qualify-imported-names-plugin/README.md).
 
 ### Add missing class methods
 
@@ -264,7 +264,7 @@ Known Limitations:
 
 ![Change Type Signature Demo](../plugins/hls-change-type-signature-plugin/change2.gif)
 
-![Link to Docs](../plugins/hls-change-type-signature-plugin/README.md)
+[Link to Docs](https://github.com/haskell/haskell-language-server/blob/master/plugins/hls-change-type-signature-plugin/README.md)
 
 ### Add argument to function
 
@@ -284,7 +284,7 @@ Convert a datatype to GADT syntax.
 
 ![GADT Demo](../plugins/hls-gadt-plugin/gadt.gif)
 
-![Link to Docs](../plugins/hls-gadt-plugin/README.md)
+[Link to Docs](https://github.com/haskell/haskell-language-server/blob/master/plugins/hls-gadt-plugin/README.md)
 
 ### Expand record wildcard
 
@@ -318,7 +318,7 @@ Provided by: `hls-eval-plugin`
 
 Evaluates code blocks in comments with a click. [Tutorial](https://github.com/haskell/haskell-language-server/blob/master/plugins/hls-eval-plugin/README.md).
 
-![Eval Demo](https://raw.githubusercontent.com/haskell/haskell-language-server/master/plugins/hls-eval-plugin/demo.gif)
+![Eval Demo](../plugins/hls-eval-plugin/demo.gif)
 
 Known limitations: