message: Update vim.searchHighlightColor in README.md
  Update the default value of `vim.searchHighlightColor` in README.md to reflect the actual default color of the search highlight.
diff: @@ -122,7 +122,7 @@ These settings are specific to VSCodeVim.
  | vim.disableExtension | Disable VSCodeVim extension. This setting can also be toggled using `toggleVim` command in the Command Palette | Boolean | false |
  | vim.handleKeys | Delegate configured keys to be handled by VSCode instead of by the VSCodeVim extension. Any key in `keybindings` section of the [package.json](https://github.com/VSCodeVim/Vim/blob/master/package.json) that has a `vim.use<C-...>` in the when argument can be delegated back to VSCode by setting `"<C-...>": false`. Example: to use `ctrl+f` for find (native VSCode behaviour): `"vim.handleKeys": { "<C-f>": false }`. | String | `"<C-d>": true` |
  | vim.overrideCopy | Override VSCode's copy command with our own, which works correctly with VSCodeVim. If cmd-c/ctrl-c is giving you issues, set this to false and complain [here](https://github.com/Microsoft/vscode/issues/217). | Boolean | false |
  -| vim.searchHighlightColor | Set the color of search highlights | String | rgba(150, 150, 150, 0.3) |
  +| vim.searchHighlightColor | Set the color of search highlights | String | rgba(150, 150, 255, 0.3) |
  | vim.startInInsertMode | Start in Insert mode instead of Normal Mode | Boolean | false |
  | vim.substituteGlobalFlag | Similar to Vim's `gdefault` setting. `/g` flag in a substitute command replaces all occurrences in the line. Without this flag, replacement occurs only for the first occurrence in each line. With this setting enabled, the `g` is on by default. | Boolean | false |
  | vim.useCtrlKeys | Enable Vim ctrl keys overriding common VSCode operations such as copy, paste, find, etc. | Boolean | true |
  