Accessibility color contrast fixes (securefederatedai#864)

* Fix incorrectly formatted link in docs

Signed-off-by: Francis Storr <francis.storr@intel.com>

* Font styling, color contrast, other accessibility updates

This update:
1. Restores Roboto and Lato fonts for most body copy, leaving Intel One Mono for code samples.
2. Adds colors (in `colors.css`)
3. Adds a new `accessibility_overrides.css` file containing CSS that improves the accessibility of the documentation and, where possible, Read The Docs. These updates remediate numerous non-conforming WCAG 2.x Level AA bugs. The use of a separate file for this hopefully makes these changes easier to manage and less likely to be accessibility overwritten in the future.

Closes securefederatedai#848

Signed-off-by: Francis Storr <francis.storr@intel.com>

* Color contrast updates for accessibility

Color contrast updates for accessibility
- update generic `a` element
- update color of links in the toggle-able read-the-docs panel
- update the color of the text in search results
- update the color of notes headers

Signed-off-by: Francis Storr <francis.storr@intel.com>

---------

Signed-off-by: Francis Storr <francis.storr@intel.com>
Signed-off-by: Parth Mandaliya <parthx.mandaliya@intel.com>

docs/_static/css/accessibility_overrides.css

@@ -4,9 +4,12 @@
     font-size: 100%;
   }
 
-
   /* links */
 
+  a{
+    color:var(--classic-blue);
+  }
+
   [role=main] a,
   footer a:not([class*=btn-neutral]){
     color: var(--classic-blue);
@@ -18,6 +21,18 @@
     color: var(--cobalt);
   }
 
+  .rst-versions.shift-up a{
+    color:var(--classic-blue-tint2);
+  }
+
+  /* read the docs meta information in toggle content */
+
+  .rst-versions .rst-other-versions{
+    color:var(--carbon-tint1);
+  }
+
+  /* end read the docs meta information in toggle content */
+
   /* end links */
 
   footer{
@@ -43,8 +58,16 @@
     margin-bottom:1.5rem;
   }
 
-  /* flow content */
+  /* search results */
+
+  #search-results .context{
+    color:var(--black);
+  }
+
 
+  /* end search results */
+
+  /* flow content */
 
   p {
     line-height: inherit;
@@ -126,7 +149,7 @@
   /* end sidebar */
 
 
-  /* =notes and similar */
+  /* notes and similar */
 
   .rst-content .note .admonition-title,
   .rst-content .note .wy-alert-title,
@@ -155,7 +178,7 @@
   .rst-content .wy-alert.wy-alert-info .admonition-title,
   .wy-alert.wy-alert-info .rst-content .admonition-title,
   .wy-alert.wy-alert-info .wy-alert-title{
-    background: var(--blue-steel);
+    background: var(--blue-steel-shade1);
   }
 
   /* code and code blocks */
@@ -176,5 +199,4 @@
     font-size:0.875rem;
   }
 
-
 }