docs(term_tab): rewrite README in markdown (#11381)

plugins/term_tab/README

@@ -1,16 +0,0 @@
-
-term_tab - 'cwd' for all open zsh sessions
-******************************************
-
-What it does:
-*************
-This plugin allows to complete the 'cwd' of other Zsh sessions. Sounds
-complicated but is rather simple. E.g. if you have three zsh sessions open, in
-each session you are in a different folder, you can hit Ctrl+v in one session
-to show you the current working directory of the other open zsh sessions.
-
-How it works:
-*************
-* It uses 'pidof zsh' to determine all zsh PIDs
-* It reads procfs to get the current working directory of this session
-* Everything is fed into zsh's completion magic

plugins/term_tab/README.md

@@ -0,0 +1,16 @@
+# term_tab plugin
+
+term_tab - `cwd` for all open zsh sessions
+
+## What it does:
+
+This plugin allows to complete the `cwd` of other Zsh sessions. Sounds
+complicated but is rather simple. E.g. if you have three zsh sessions open, in
+each session you are in a different folder, you can hit `Ctrl+V` in one session
+to show you the current working directory of the other open zsh sessions.
+
+## How it works:
+
+* It uses `pidof zsh` to determine all zsh PIDs
+* It reads procfs to get the current working directory of this session
+* Everything is fed into zsh's completion magic

themes/agnoster.zsh-theme

@@ -116,6 +116,17 @@ prompt_git() {
       prompt_segment green $CURRENT_FG
     fi
 
+    local ahead behind
+    ahead=$(git log --oneline @{upstream}.. 2>/dev/null)
+    behind=$(git log --oneline ..@{upstream} 2>/dev/null)
+    if [[ -n "$ahead" ]] && [[ -n "$behind" ]]; then
+      PL_BRANCH_CHAR=$'\u21c5'
+    elif [[ -n "$ahead" ]]; then
+      PL_BRANCH_CHAR=$'\u21b1'
+    elif [[ -n "$behind" ]]; then
+      PL_BRANCH_CHAR=$'\u21b0'
+    fi
+
     if [[ -e "${repo_path}/BISECT_LOG" ]]; then
       mode=" <B>"
     elif [[ -e "${repo_path}/MERGE_HEAD" ]]; then