[clangd] Update docs to mention YCM integration and new LSP features

[ilya-biryukov]

docs/clangd.rst

125 ↗

(On Diff #181774)

Given how little information we actually provide for each option here (it's literally just pointers to the docs), maybe make this a list instead to avoid copy-pasting between those two?
Something like:

You can use Clangd in vim with one of the following plugins:

• YouCompleteMe, see installation instructions.
• LanguageClient-neovim, see clangd wiki page for instructions.

129 ↗

(On Diff #181774)

I believe this does not mention how to install clangd, though (and libclang-based is still the default, right?) Do we want to mention how to configure it to use clangd here?

[kadircet]

docs/clangd.rst

129 ↗

(On Diff #181774)

That's actually the reason I haven't submitted this one for review. I am preparing a PR to YCM folks which will hopefully include clangd in installation process

[kadircet]

• Revert YCM related parts

[kadircet]

• Rebase

clang-tools-extra/trunk/docs/clangd/index.rst

 | Signature Help                      | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
 | Document Highlights                 | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
 | Rename                              | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
 | Source hover                        | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
-| Find References                     | Yes        |   No     |
-+-------------------------------------+------------+----------+
-| Code Lens                           | Yes        |   No     |
+| Find References                     | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
 | Document Symbols                    | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
 | Workspace Symbols                   | Yes        |   Yes    |
 +-------------------------------------+------------+----------+
-| Syntax and Semantic Coloring        | No         |   No     |
+| Code Lens                           | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Code folding                        | No         |   No     |
+| Code folding                        | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Call hierarchy                      | No         |   No     |
+| Extract Local Variable              | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Type hierarchy                      | No         |   No     |
+| Extract Function/Method             | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Organize Includes                   | No         |   No     |
+| Quick Assist                        | Yes        |   No     |
++-------------------------------------+------------+----------+
+| Hide Method                         | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Quick Assist                        | No         |   No     |
+| Implement Method                    | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Extract Local Variable              | No         |   No     |
+| Gen. Getters/Setters                | Yes        |   No     |
 +-------------------------------------+------------+----------+
-| Extract Function/Method             | No         |   No     |
+| Syntax and Semantic Coloring        | No         |   No     |
 +-------------------------------------+------------+----------+
-| Hide Method                         | No         |   No     |
+| Call hierarchy                      | No         |   No     |
 +-------------------------------------+------------+----------+
-| Implement Method                    | No         |   No     |
+| Type hierarchy                      | No         |   No     |
 +-------------------------------------+------------+----------+
-| Gen. Getters/Setters                | No         |   No     |
+| Organize Includes                   | No         |   No     |
 +-------------------------------------+------------+----------+
 
 Editor Integration
 ==================
 
 Any full-featured Language Server Protocol Client implementation should work
 with :program:`Clangd`. This `list
 <https://langserver.org/#implementations-client>`_ contains information about