ReadMe: Add hugo config custom params documentation (#433)

Author: lamATnginx

README.md

@@ -87,3 +87,41 @@ You can reuse the content of any file in the includes directory using the follow
 ```md
 {{< include "filename.md" >}}
 ```
+
+### Hugo Config
+
+We have several **optional** custom options to add to your config `toml` or `yaml`.
+
+### `searchOnPage`
+Option to add a coveo searchbar on top of the coveo filters on a search results page.
+
+Example:
+```toml
+[params]
+  searchOnPage = true
+```
+### `featureFlags`
+Options to add feature flags. Syntax denoted by prefix `disable_`.
+
+Example:
+```toml
+[params]
+  ...
+  [params.featureFlags]
+      disable_coveo = true
+      disable_qualtrics = true
+```
+
+### `typographer`
+Options to translate plain ASCII punctuation characters into typographic-punctuation HTML entities. More info [here](https://gohugo.io/configuration/markup/#typographer).
+
+Example:
+```toml
+[markup]
+  ...
+  [markup.goldmark.extensions.typographer]
+      rightDoubleQuote = '&quot;'
+      leftDoubleQuote = '&quot;'
+      rightSingleQuote = '&apos;'
+      leftSingleQuote = '&apos;'
+```