Fix zplug syntax

The space before "plugin" raises an error

README.md

@@ -23,7 +23,15 @@ Install
 Using the [Homebrew]( https://brew.sh ) package manager:
 
     brew install zsh-history-substring-search
-    echo 'source /usr/local/share/zsh-history-substring-search/zsh-history-substring-search.zsh' >> ~/.zshrc
+    echo 'source $(brew --prefix)/share/zsh-history-substring-search/zsh-history-substring-search.zsh' >> ~/.zshrc
+
+Using [Fig](https://fig.io):
+
+Fig adds apps, shortcuts, and autocomplete to your existing terminal.
+
+Install `zsh-history-substring-search` in just one click.
+
+<a href="https://fig.io/plugins/other/zsh-history-substring-search" target="_blank"><img src="https://fig.io/badges/install-with-fig.svg" /></a>
 
 Using [Oh-my-zsh](https://github.com/robbyrussell/oh-my-zsh):
 
@@ -35,22 +43,61 @@ Using [Oh-my-zsh](https://github.com/robbyrussell/oh-my-zsh):
 
         plugins=( [plugins...] zsh-history-substring-search)
 
-3. Source `~/.zshrc`  to take changes into account:
+3. Run `exec zsh`  to take changes into account:
 
-        source ~/.zshrc
+        exec zsh
+
+Using [zplug](https://github.com/zplug/zplug):
+
+1. Add this repo to `~/.zshrc`:
+
+        zplug "zsh-users/zsh-history-substring-search", as:plugin
+
+Using [antigen](https://github.com/zsh-users/antigen):
+
+1. Add the `antigen bundle` command just before `antigen apply`, like this:
+
+``` 
+antigen bundle zsh-users/zsh-history-substring-search
+antigen apply
+```
+ 
+2. Then, **after** `antigen apply`, add the key binding configurations, like this:
+ 
+```
+# zsh-history-substring-search configuration
+bindkey '^[[A' history-substring-search-up # or '\eOA'
+bindkey '^[[B' history-substring-search-down # or '\eOB'
+HISTORY_SUBSTRING_SEARCH_ENSURE_UNIQUE=1
+```
+
+Using [Zinit](https://github.com/zdharma-continuum/zinit):
+
+1. Use the `Oh-my-zsh` Zinit snippet in `~/.zshrc`:
+
+        zinit snippet OMZ::plugins/git/git.plugin.zsh
+
+2. Load the plugin in `~/.zshrc`:
+
+        zinit load 'zsh-users/zsh-history-substring-search'
+        zinit ice wait atload'_history_substring_search_config'
+
+3. Run `exec zsh` to take changes into account:
+
+        exec zsh
 
 Usage
 ------------------------------------------------------------------------------
 
 1.  Load this script into your interactive ZSH session:
 
-        % source zsh-history-substring-search.zsh
+        source zsh-history-substring-search.zsh
 
     If you want to use [zsh-syntax-highlighting][6] along with this script,
     then make sure that you load it *before* you load this script:
 
-        % source zsh-syntax-highlighting.zsh
-        % source zsh-history-substring-search.zsh
+        source zsh-syntax-highlighting.zsh
+        source zsh-history-substring-search.zsh
 
 2.  Bind keyboard shortcuts to this script's functions.
 
@@ -73,6 +120,10 @@ Usage
           bindkey "$terminfo[kcuu1]" history-substring-search-up
           bindkey "$terminfo[kcud1]" history-substring-search-down
 
+      Users have also observed that `[OA` and `[OB` are correct values, 
+      _even if_ these were not the observed values. If you are having trouble
+      with the observed values, give these a try.
+
       You might also want to bind the Control-P/N keys for use in EMACS mode:
 
           bindkey -M emacs '^P' history-substring-search-up
@@ -161,6 +212,9 @@ default values.
   receive globally unique search results only once, then use this
   configuration variable, or use `setopt HIST_IGNORE_ALL_DUPS`.
 
+* `HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_TIMEOUT` is a global variable that
+  defines a timeout in seconds for clearing the search highlight.
+
 
 History
 ------------------------------------------------------------------------------

zsh-history-substring-search.zsh

@@ -406,7 +406,24 @@ _history-substring-search-end() {
 
   # For debugging purposes:
   # zle -R "mn: "$_history_substring_search_match_index" m#: "${#_history_substring_search_matches}
-  # read -k -t 200 && zle -U $REPLY
+  # read -k -t 200 && zle -U -- "$REPLY"
+
+  #
+  # When this function returns, z-sy-h runs its line-pre-redraw hook. It has no
+  # logic for determining highlight priority, when two different memo= marked
+  # region highlights overlap; instead, it always prioritises itself. Below is
+  # a workaround for dealing with it.
+  #
+  if [[ $_history_substring_search_zsh_5_9 -eq 1 ]]; then
+    zle -R
+    #
+    # After line redraw with desired highlight, wait for timeout or user input
+    # before removing search highlight and exiting. This ensures no highlights
+    # are left lingering after search is finished.
+    #
+    read -k -t ${HISTORY_SUBSTRING_SEARCH_HIGHLIGHT_TIMEOUT:-1} && zle -U -- "$REPLY"
+    region_highlight=( "${(@)region_highlight:#*${highlight_memo}*}" )
+  fi
 
   # Exit successfully from the history-substring-search-* widgets.
   return 0