Update site index page with lighter font

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**What type of PR is this:**

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/kind documentation

**What does this PR do / why we need it:**

Updates the website so the index page isn't "shouting" at you with the
bolded text. Changes it to a softer weighted font.

**Which issue(s) this PR fixes:**
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N/A

Signed-off-by: Charlie Drage <charlie@charliedrage.com>

docs/website/src/css/custom.css

@@ -33,3 +33,11 @@
 html[data-theme='dark'] .docusaurus-highlight-code-line {
   background-color: rgba(0, 0, 0, 0.3);
 }
+
+.bannerProjectTagline_src-pages-index-module {
+  font-weight: 400;
+}
+
+.button {
+  font-weight:500;
+}