fix register part of documentation for caffeine & guava instrumentation + fix typo in method name

Signed-off-by: Petar Heyken <mail@petar-heyken.de>

Author: pheyken

prometheus-metrics-instrumentation-caffeine/src/main/java/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.java

@@ -25,7 +25,8 @@
  * <pre>{@code
  * // Note that `recordStats()` is required to gather non-zero statistics
  * Cache<String, String> cache = Caffeine.newBuilder().recordStats().build();
- * CacheMetricsCollector cacheMetrics = new CacheMetricsCollector().register();
+ * CacheMetricsCollector cacheMetrics = new CacheMetricsCollector();
+ * PrometheusRegistry.defaultRegistry.register(cacheMetrics);
  * cacheMetrics.addCache("mycache", cache);
  *
  * }</pre>
@@ -87,7 +88,7 @@ public void addCache(String cacheName, AsyncCache<?, ?> cache) {
    *
    * @param cacheName cache to be removed
    */
-  public Cache<?, ?> nremoveCache(String cacheName) {
+  public Cache<?, ?> removeCache(String cacheName) {
     return children.remove(cacheName);
   }
 

prometheus-metrics-instrumentation-guava/src/main/java/io/prometheus/metrics/instrumentation/guava/CacheMetricsCollector.java

@@ -23,7 +23,8 @@
  * <pre>{@code
  * // Note that `recordStats()` is required to gather non-zero statistics
  * Cache<String, String> cache = CacheBuilder.newBuilder().recordStats().build();
- * CacheMetricsCollector cacheMetrics = new CacheMetricsCollector().register();
+ * CacheMetricsCollector cacheMetrics = new CacheMetricsCollector();
+ * PrometheusRegistry.defaultRegistry.register(cacheMetrics);
  * cacheMetrics.addCache("mycache", cache);
  *
  * }</pre>